Jimmy Fallon is up for the Rahm Emanuel challenge.
In a one-on-one interview Thursday, Chicago's mayor said he'd spoken to the new "Tonight Show" host by phone about doing the Chicago Polar Plunge on March 2.
A day earlier, Emanuel accepted an invitation by Fallon to appear on the program, but only if the comedian took part in the annual dip into an icy Lake Michigan to benefit the Special Olympics.
"Let me check my schedule," was Fallon's response to the challenge, the mayor said.
Emanuel said Fallon noted that he wouldn't do it just because the mayor asked him but because "Chicago is number one" in viewers.
The Second City was the top market in viewership for Monday's debut of "The Tonight Show Starring Jimmy Fallon." One rating point equals 35,000 households in Chicago
The dialog between the two men began after Fallon said Emanuel had an open invitation to make a guest appearance on the show.
"All he has to do is make a phone call," Fallon said. "He can host if he wants to. I'm scared of that guy."