Dawn of War and Space Marine had some good ones
There Is Only War
Taint Your Wagon
Success is Measured in Blood: Kill 500 enemies using Melee weapons.
And all these have to be read in a cockney accent. (It's the law).
Red Ones Go Fastah!: Create a Customized look for any race in the Army Painter in Dawn of War II.
E's a Zogging Nurse!: Revive your teammates 30 times during online ranked play.
Can't touch dis: Kill 2,500 enemies as the Ork Mekboy.
And you simply can't beat:
Nice Hat: Complete the Ork campaign on any difficulty.
(Yes, he brought an entire subsector to its knees, over a hat.)
Also, WHOOO! 2000 POSTS!