If Neil Patrick Harris is trying to embarrass his twins when they grow up, he's going about it the right way!

On Thursday's Late Show With David Letterman, the How I Met Your Mother star, and proud papa of seven-month-old twins Giedon and Harper, revealed he and partner David Burtka are making a monthly calendar of their twins -- complete with holiday-theme dress!

Harris revealed to Letterman, "We do one a month. We're doing a calendar so that when they're older, we can humiliate them and embarrass them. We go to Party City and get all the great stuff."

Loves it!

But the pics prompted Letterman, who is a parent himself, to quip, "You know that babies are more than party props?"


Check out the rest of the twin's adorable holiday calendar pics (you wont believe the Cinco de Mayo shot for May!) after the jump ...