As someone rather well-endowed in the caboose department, I've always been amused by Sir Mix-a-lot's classic. It's catchy. It's funny.
Burger King is trying to promote their new kids' meals--square meals. As such, they've adapted Sir Mix-a-lot's song to "I like square butts." The BK king raps and checks the right angles of the ladies' butts as they shake their righteous booties. Sponge Bob Square Pants makes a few appearances too, thus the commercial creates an interesting (and I would suggest disturbing) series of contrasts between children's cartoons, kid's meals, and songs about sex and butts.
Thoughts? The video premeried during halftime (go Tarheels!) so I haven't been able to find it online yet.