Stephen Colbert has a Plan B if there's an LIRR strike.

The Comedy Central host asked Mayor Bill de Blasio if there's an LIRR strike, "can we just crash at Gracie Mansion?" "You're going to have to talk to my wife about that," the mayor responded.

De Blasio made his debut on "The Colbert Report" on Wednesday night, where Colbert repeatedly cried "you're a socialist" to the famously progressive mayor and said that de Blasio wanted to bring us back to the 1980s, "the bad days of the squeegee men, the rampant crime and leg warmers.

De Blasio, for his part, said "the leg warmers weren't so bad," but also touted his universal pre-K program. When Colbert asked "why is it my problem if someone can't afford pre-K [and] gets pre-K? Let them work for it themselves," de Blasio quipped "those 4-year-olds are not yet in the workforce." Colbert responded "that's another problem -- those little hands change bobbins so well."

On the topic of the looming LIRR strike, de Blasio brushed off the worries about his upcoming trip to Italy, saying it was under Gov. Andrew M. Cuomo's jurisdiction. This led to Colbert taunting him that it was "not my problem! Not my problem! Bring me the bowl! Bring me the bowl so that Pontius Pilate may wash his hands!"

Colbert tried to get de Blasio to admit that his predecessor, Michael Bloomberg was a "great mayor," leading de Blasio to concede that Bloomberg "did some good things," but the mayor insisted "in the end, [Bloomberg] did not address income inequality, he did not address stop-and-frisk."

"You did address stop-and-frisk -- you ended stop-and-frisk as we know it," Colbert said. "But now if I randomly grope young black men, I seem like a weirdo."

The de Blasio family also attended the show, along with what appeared to be several of Chiara and Dante's friends, according to the pool report.

Colbert also poked fun at the reports earlier this week that he had "bullied" de Blasio to attend the show via Twitter. "According to the Internet, I bullied him into accepting an invitation on my show. That's right. It's my biggest coup since landing Joe Biden on Tinder. Swipe right! Anyway, the mayor will be on later, and Joe Biden -- even later," Colbert said with a grin.