After having a 360 for a few months I found that there are a few strange, funny, scary achievments around. My best so far would have to be Fable 2's "The Chicken kicker", gained by kicking a gicken a few metres along the ground or in the air. With so many 360 games around and so many achievments to be unlocked i would guess that there would be quite a few interesting achievments to be found.

Sorry for putting no text in my initial post the first time. Accidentally pressed enter when I wasn't ment to!

Waits

EDIT: And now that i'm done waiting...I really couldn't tell you which was the strangest...

Hero-of-Legend:
(no text)

Hmm, isn't that the call of the mod?

I think one of the ones on Halo 3 is pretty funny. Kill a certain amount of enemies with a Needler. Or a HL2 one where you have to pin the Combine soldier to the billboard :P

Strangest one I've seen is "Irony" in Bioshock.

There should be an achievement on Gears of War 2 for finding the toaster. That'd be a weird achievement.

The Little Rocket Man achievement in HL2: Episode 2. Now that's an achievement.

Dead rising had some weird ones.

Costume Party
Place novelty masks on at least 10 zombies.

I was just kickin' chickens about in Fable 2, and ping. Achievement unlocked.

Madnezz:
The Little Rocket Man achievement in HL2: Episode 2. Now that's an achievement.

Anyone who carries that stupid bastard through 5 levels, two of them vehicle sections, one with a goddamn chopper on your arse, deserves that goddamn achievement.

I'm proud to say, I'm among the select few whores who were anal enough to get that little bastard on the rocket.

Rock Snob was an achievement I kinda enjoyed, 'cause I got that by accident.

Madnezz:
The Little Rocket Man achievement in HL2: Episode 2. Now that's an achievement.

I can't believe I actually did that one. Also, the One Free Bullet achievement in Episode 1. What the hell, Valve.

There's an achievement in Alien Hominid for decapitating, like, 50 dudes in a row without touching the ground. Something tells me they didn't playtest that one properly, because there's only one spot in the entire game where that's possible, and even then it's a weird-looking struggle.

I did little rocket man the other day, and found it wasn't as hard as it seems. Whenever there is fighting just drop him and go back later, and in a few places you can either leave him or shoot him to the next area with the grav gun, and recover him after a few blissful gnome-free sections. You also don't need to take him through the end of the game, only up to white forest. Although I have to admit, that bloody chopper section was a royal pain in the ass.

While I don't have a 360 for achievements, I did get a tome unlock called "Aaaaaaaargh" for death by falling 5 times in WAR, as well as something like "gurgle" for drowning 10 times.

Getting the 800,000 point achievement in GH2 was fucking awesome. I think it's time to go back and finally clock the big 1 mil

Seven Day Survivor in Dead Rising. Go spending fourteen hours playing a video game straight.

dirty dirty horde in gow2 is probly my weirdest

threw someone out of a window in saints row 2. wasn't expecting that

Radelaide:
Or a HL2 one where you have to pin the Combine soldier to the billboard :P

Half Life 2: Episode 2

Hot Potatowned: Kill a Combine with is own grenade (not weird at all but the best name ever)
Little Rocket Man: Blast him into space, go on, blast the little bugger!

Left 4 Dead

Outbreak: Catch a rare form of infection then pass it on. Probably the oddest achievement ever in that it's a viral one that is quite literally passed around between players. There is no way to 'earn' it, you just have to get boomered by the right person.

The one you get for putting live grenades in peoples pockets in Fallout, i was doing it to be a sick bastard i didn't know i got rewarded for it!

The Orange Box

"Flushed" - Kill an enemy with a toilet.

I'd like to kill that gnome with a toilet (damn Little Rocket Man achievement).

sitting on the couch next to jackies girlfriend for a few minutes in the darkness.

probably the first three trophies i unlocked on Warhawk. these are hidden trophies, mind.

one for running into your own airial mine
one for getting killed by mines 6 times in a round
and one for getting killed in a warhawk, by someone using binocs (for 360 gamers, this is considerable. since warhawks move about like dragonflies, and binocs are pretty much the Splazer)

Completionist achievement in Mass Effect, having only played through half of the story. Well it confused me at the time!

Whilst I don't have it (or, indeed, the game) Left 4 Dead has the most meta achievement ever. Zombie Genocidest. Kill 53595 zombies. Why 53595? It's one more than Dead Rising's Zombie Genocider achievement.

skeet shooter in Dark Sector

AWWW SKEET SKEET

I do rather love the Half Life 2 "Bonebreaker" achievement, but who doesn't love bricking zombies in the face?

Simski:
Dead rising had some weird ones.

Costume Party
Place novelty masks on at least 10 zombies.

DirkGently:
Seven Day Survivor in Dead Rising. Go spending fourteen hours playing a video game straight.

I was going to mention Dead Rising, I think a lot of the achievments in that game are pretty weird.
Stoopid 360 being stolen kinda ruined that for me.

In Shadowrun, there is an achievment called "Catch Shadowrun fever" with the explanation "Catch it!". Turns out you catch Shadowrun fever when you teabag someone.

Half Life 2: Episode 2.

The one where you have to kill every grub in the game..I was awarded that 1st time through. and my thoughts were this: "Yay! Valve shares my ambition for slug genocide!"

Numeric God in Soul Calibur IV, if just because it is practically impossible to actually intend to get the achievement. The last two digits of the remaining match time have to match the last two digits of your current play time. I can not even begin to think of a way to set this up, short of sitting down and calculating the time it takes to perform every move to the last millisecond.

As for ones I just didn't expect, TH Proving Grounds Thug Check Distance achievement. I didn't mean to get it, I just enjoyed bashing into people. And then I knocked one off a pier and apparently sent him over 150 feet.

taking the whole taxi ride on gta 4

'Is that a spider?' RvB reference in Gears of War for sticking people with grenades. If I recall correctly anyway. Laughed my ass off whichever game it was.

There's one challenge (kind of like achievements) on call of duty 4 I wasn't even aware of, another one I'm a little hazey on, I believe you had to shoot through a wall and kill an enemy by hitting an explosive device. I unlocked maybe 4-5 challenges with that one shot too.. "Claymore," "Clay More," "Backdraft," etc.. Really wild scoring 2000+ points in a single multiplayer match.

A lot of achievements you get in dead rising. I was determined to knock down ten zombies with a bowling ball just because I bowl, I was totally unawawre of the achievement.

WoW achievment actually.
Going Down? you have to fal 65 yards without dying, lot harder to do on purpose than you would tthink. I ended up getting it when I went down a steep slope on a mount. I just let go of the mouse and keyboard and kciked back as I had thought death was inevitable. I land and all but 15 hp is taken out and I get the damn achiievment. Not really wierd, just was expecting death instead of an achievment. Did the same thing in COD4 with the falling ones. Both on mother fucking accident. I fall alot.

Dry Eyes In Alone in the dark