Credit Bill Hader for giving John Mulaney credit throughout this panel chat on tonight's Late Show with David Letterman, as Hader cracks up explaining how he cracks up whenever he performs the "Stefon" character on Saturday Night Live's Weekend Update.

"I've laughed every — dress and air — I've laughed every single time, because it's just ridiculous," he said, before bursting into another round of giggles. "You're not supposed to laugh. But Seth Meyers will start to go, and I'll see cue guy, the cue card guys will start laughing, and then, now it's gotten to the point where the guy putting on my mic will go, 'You are dead, buddy. You are going to laugh first thing out of the gate.' And then sometimes John Mulaney will change things as we walk out. I'll be walking out and he'll go, 'The club promoter's name is now Gay Liotta.' I'm like, 'Why did you just do that to me?'"

You've read about how Hader and Mulaney came up with Stefon. Now watch and listen to Hader explain it (and his new fan base) to Letterman!