Hardest achievement you've ever gotten?

I'm sure this thread has been done before, but i haven't seen any here so i'm sorry if its been done before.

These are the 3 hardest i've gotten, and an honorable mention.

1. Platinum Artist
Finished the Endless Setlist in Band World Tour on Expert

Rock Band achievement. I played this with my cousin. It took us 5.5 hours to finish. We failed Green Grass and High Tides like 4 times.

2. Escaped from Squashtrich
You escaped without being stomped by the Squashtrich.

A Blue Dragon achievementIf anyones gone for this achievement they know how insane it is. You have to tap A so fast its ridiculous.

3. Dig
Dig through the entire area on any Round!

This is from Dig Dug. I did this 3 times before it unlocked the achievement. one time i even did it on the demo on accident.

Honorable Mention Aperture Science
Earn gold medals on all Portal challenges.

If it wasn't for YouTube, this would have been impossible. Very tough achievement imo

So what about you guys?

from hardest to easiest

aperture science (portal)

fly the co-op (gta4)

grand pearl poo-bah (hexic)

rsv 1 and 2 on veteran

mile high club (cod4)

saint (dead rising)

Beating Devil May Cry 4 on Dante Must Die mode

Getting 100% completion in GTA4

Beating Through the Fire and Flames on Expert

LOL I WISH.........My hardest was probly beating GH3 on expert.

mm dont know the name of the achievement but it was the one where you had to kill 3 people with the spartan laser in 1 shot (halo3)link-a-link

The hardest...ummmm "EAT THE CROWN" Pac Man Championship Edition.

Easiest....."LOSER" lose 3 fights in a row in Prizefighter

I've got a lot of achievements that really didn't require skill, just a lot of time investment (find all flags/kill all templars in Assassin's Creed, finding all the orbs/stunt markers/doing all the races on Crackdown, getting Seriously an THIS!IS!ANNEX! on Gears)

The hardest I'd probably say was Mile High Club on CoD4 and Psych out on Crackdown

lol 22000 is allo off gamer-score