This video—hat tip to Turf Show Times—of St. Louis Rams rookie "The Human" Isaiah Pead rapping at an NFLPA rookie premiere event does exactly what it says on the tin: You'll see Giants rookie David Wilson freestyling over a pretty generic beat, then he'll hand it to Isaiah Pead who will do a little more of that. If you like that sort of thing, you are hereby advised to press play (and maybe even full-screen) on the following video:
If you're the kind of person who gets uncomfortable watching other people sing on karaoke nights, especially when they mess up a word in the middle of the chorus of "Land of Confusion," or who can't watch the opening rounds of American Idol, I would recommend going no further. They're both competent, but freestyle rapping is in general going to make you feel like you're watching the British version of The Office.
Meanwhile, at Rams Park: Steven Jackson spends 72 consecutive hours mastering a freestyle rap about how he should get all the Rams' carries and his knees making that noise isn't really such a big deal.