By Joey Nolfi
March 20, 2018 at 09:30 AM EDT

Though he’s a seasoned pro with eight years as a Saturday Night Live repertory player under his belt, Bill Hader still accidentally breaks character if the material is right — or a pesky scene partner coaxes it out of him.

The actor returned last weekend to host SNL for the second time since his 2013 departure from the variety series, bringing with him perhaps his most recognizable character: club-loving partier Stefon. And Hader couldn’t make it through the sketch without cracking.

“John Mulaney writes Stefon and is our dear friend, and he came out as Stefon’s lawyer…. As well as a ‘conceptual piss artist.'” Hader, unable to control his laughter while recalling the exchange, told fellow SNL alum Seth Meyers on Monday’s episode of Late Night. “And he whispered in my ear to make me laugh, ‘My girlfriend works at Yoshinoya Beef Bowl,’ which is a restaurant chain in L.A.”

Hader later giggled his way through a discussion about another scene from Saturday’s episode in which he played an old, wheelchair-bound man, Horace, who’d taken pills for erectile dysfunction just before entering a party with his much younger girlfriend (Cecily Strong).

“It kicked in and it only lasts for a couple minutes, so they had to try to take the opportunity to get pregnant,” Hader recalled, adding that censors don’t allow for simulated sex during SNL‘s broadcast, and that show staff warned him he couldn’t move a muscle while Strong sat on his lap. But, as Meyers pointed out, he was able to move Horace’s motorized wheelchair, which he promptly backed up into a table surrounded by the other actors playing party guests.

“I backed up and I knew I hit something but I didn’t know what it was,” Hader said, chuckling once again. “I could hear Melissa [Villaseñor] behind me going, ‘It’s me!'”

Watch Hader’s interview with Meyers above, and head here for EW’s full recap of Saturday’s episode of SNL.