My most recent mistake...

Plain simple:
While RDJ is in black face, there are several points throughout the film that make the punchline this: the meta-meta of RDJ playing a WHITE MAN (one who overcompensates in being hired for the role of playing a BLACK MAN) is ultimately a crack on white people appropriating Black culture. So, context makes that, in itself, hilarious.

Here is a discussion on the film, where white people are victimizing selves and whining about bullshit. Ahem:

Shane said,
March 9th, 2008
Typical nonsense, the usual double standard. It’s the same thing with black comedians ripping on white people, total acceptable, but lets see a white comedian tear into black people and listen to the out-cry.

Hey there, dumbass. <3

Brandon T. Jackson, who plays "Alpha Chino" serves as a direct foil to a lot of the cultural appropriation happening up in there. It's fairly simple, and I don't think it's "cooning." Robert Downey Jr. is excellent in this movie. Maybe I'm still teetering from his greatbigcomeback in IRONMAN. (gyeah!) Jack Black is Jack Black. Ben Stiller is Ben Stiller. Still a pretty simple fratboy film. Pardon my yawning.