Poor Jimmy Fallon. One minute, you're the only game in town wearing a pair of much-discussed tight pants; the next, you're being toppled from your throne by a very volatile Jennifer Lopez, whose tight pants are so much tighter than yours.

This musical battle of wills (and pants!) was part of Monday's "The Tonight Show" lineup, and it had all the makings of a wholesome dance-off in which both parties learned an important lesson about friendship and sharing...

...that is, until J-Lo removed an earring and vowed to start cutting people if Jimmy didn't take his pants and skedaddle. Which he did, and we don't blame him.