I can't explain exactly why this is so funny. It just is. The fat kid, the Urkel, the husky riverdance, the commentary, all of it.
Jack fuckin murked this thing with the double-handed diagonal air punches. Steve (like Urkel), unable to continue his frantic Michael Jackson-like spasms, pulls out some wack jumping spider move. Pfft. Jack wins this shit hands down.
"Ooo HE'S LIKE FIGHT...DANCING." You're damn right he is.