Jay Leno mocks 'douche bag' Billy Bush as he 'tags in' for Jimmy Fallon on 'Tonight Show'

Jay Leno stopped by Jimmy Fallon's Tonight Show on Monday. As on past visits, the former Tonight Show host filled in on part of his successor's monologue, "tagging in" after Fallon claims he pulled a muscle.

Leno joked about Donald Trump, Hillary and Bill Clinton, Anthony Weiner and the recent Republican and Democratic national conventions.

Since it was Halloween, Leno also made a few holiday-themed jokes, including one about Hillary Clinton getting scared when a trick-or-treater showed up dressed as "a lie detector."

And Leno, who's still a member of the NBC family with his Jay Leno's Garage show on CNBC, didn't take long to mock former NBC employee Billy Bush, who left the Today show following his involvement in a lewd, hot-mic conversation from a 2005 Access Hollywood appearance by Trump.

See photos of Jay Leno through the years:

Read more: Billy Bush, NBC Reach Settlement Over Donald Trump Tape

"I had a great costume this year," Leno said. "Earlier tonight I put a douche bag on my head, went out as Billy Bush."

He went on to suggest that Trump "hire Billy," claiming that "this way he could grab Bush whenever he wanted," alluding to Trump's comment about grabbing women by their genitals.

Fallon tagged back in during a series of "The economy is so bad...;" jokes, even throwing out a few himself.

"Anthony Weiner is faxing people pictures of his junk," Fallon said, later adding, "Instead of paying for heat, people are huddling around exposing Samsung phones just for the warmth."

Watch Leno's full substitute monologue above.

Read more: Billy Bush and the New Ethics of Entertainment Journalism

See photos of Billy Bush through the years: