Credit: Jason LaVeris/FilmMagic

Jon Hamm has plenty of friends with kids -- and he's not interested in having any of his own, thank you very much.

"I'd be a terrible father!" the Mad Men hunk, 41, tells Us Weekly. (As Don Draper on AMC's smash, the Golden Globe-winning actor plays a devoted if tortured father of three.)

Explains Hamm, now on the big screen in Friends with Kids, costarring and directed by Jennifer Westfeldt, his love of 14 years: "I see my friends who have children and I'm like, 'Dude, how are you even upright, much less here at work at 6 a.m.?'"

One of those friends with kids is January Jones, who plays his frosty ex-wife Betty on the show, who has a six-month-old son, Xander.

"Xander's cute as a button!" Hamm raves.

Hamm's girlfriend Westfeldt, 42, recently mused to the New York Times about why they never started a family.

"I've thought about this a lot lately. I never thought I'd be this age and not have kids," Westfeldt confessed. "But my life has also gone in a million ways I never anticipated. I kept feeling like I'd wake up with absolute clarity, and I haven't. And we have a pretty great life together. The chance that we'll regret it doesn't seem like a compelling enough reason to do it. I may wake up tomorrow with that lighting bolt, and I'll have to scramble to make it happen."