Well, I'll tell you what it is.
Once one of your ass cheeks gets moving to a groove, you know you got something, but when your other ass cheek starts moving in correspondence to the groove, you know you got some funk going on, and they start moving together in a perfect perpetual rhythm! Oh yeah!
EDIT: What explains lengthened daylight across Antarctica (south)?
Lurked moar, couldn't find a proper answer based on FEt.