Phantom Spunker,
I detect your sarcasm, but check this out:
This would take INCREDIBLY subtle performances to fake. 
My verdict so far: real. Although I have no idea why they cut the feed. And if Pfizer [the show sponsor] has a new Alopecia drug released the same day [source?], that's amazing.
My biggest question is: why would he have been laughing after the joke initially the way he was if it was fake?
And it wasn't one of those laughs that was a continuation of the previous joke.
Phantom Spunker: did you get the initial joke? I'm not even sure if I put it together, initially, because Will wasn't sitting next to Jada [for some reason?]. I do vividly recall GI Jane and Demi Moore's hairstyle in the movie, but I thought it may be just a "strong woman" comparison.
What is your assessment on this?
What do you make of it?
Matt,
My personal opinion is it's not worth burning any mental energy on these freaks. They're all weirdos, how they present themselves is contrived, and whether it's real or fake, it's still pathetic.
I'll now contradict myself by elaborating, but yeah, looks real. Remember, Will Smith is an absolute fruit bat. As stated, first he's laughing along (as they're supposed to), then he remembers he's dating a miserable skinhead bitch who's going to punish him later for laughing. He's also desperate to shake the image of himself as an emasculated deadbeat father and husband, so he runs on stage, tries to look the part, but throws a pathetic slap. Chris Rock was genuinely taken aback and didn't know how to respond, too.
Slight tangent, but I always avoid any film with Will Smith, John Travolta, Tom Cruise or The Rock in it - because I cannot stand them.