The former host tagged in to finish the monologue after current emcee Jimmy Fallon "pulled a muscle" delivering a punch line. For approximately three minutes, Leno, 65, lobbed semi-NSFW political jokes aimed at Bill and Hillary Clinton's marriage, the state of the Republican party and the recent Ted Cruz campaign ad that was pulled because it featured a porn star.
"The campaign said they hired the porn star because they thought she could make Ted Cruz easier to swallow," Leno joked.
Firing back at the audience's shock at such a risqué joke, he said, "I don't care. They can't fire me."
Leno's homecoming was clearly well welcome. At several points, Fallon audibly guffawed in the background at the edgier jokes than Leno typically told during his tenure as hosting The Tonight Show which ended in February 2014).
In October, Leno stopped by The Tonight Show in New York City and delivered a similarly politically skewed monologue.
Before wrapping up this past Wednesday, Leno, eventually joined by Fallon, 41, took on global warming.
"The Earth is as hot as it's ever been," Leno started. "It is so hot Bill Cosby is slipping his dates a chill pills. It is so hot immigrants are coming across the border on slip n' slides. That's how it is! It is so hot Donald Trump hit on Megyn Kelly just to get the cold shoulder."
Fallon, now recovered from his "injury," jumped in and added, "It is so hot instead of Red Lobster, Beyoncé is taking his ass to Dairy Queen."
The Tonight Show, which is airing from Los Angeles this week, airs weeknights (11:35 p.m. ET) on NBC.