Jay Leno surprised fans during Jimmy Fallon’s Clean Cut Comedy Tour. At the end of the act in LA, Fallon said, “This next guy is old. Really old. But he’s funny and could have a future . . . Please welcome Jay Leno.” Leno did a routine, then warmly hung with Fallon backstage, and Fallon effused he’d been a great supporter. But Leno got a parting shot in: “Jimmy’s tour is ‘Clean Cut Comedy’ because he and the other acts have no cursing,” said a source. “So Leno looked at Jimmy and said into the mic, ‘[Bleep] you.’ ”