Neil Patrick Harris may be known for bringing the comedy on the CBS hit show 'How I Met Your Mother,' but his biggest fans are his 3-month-old twins, according to OK! Magazine.

Harris took to Twitter to share a major milestone for twins Gideon Scott and Harper Grace: laughing.

"The tots both started laughing. On the same day," the proud poppa tweeted. "I'm now obsessed with getting them to do it. Babies laughing is like opium."

Harris and partner David Burtka welcomed their bundles of joy last October through a surrogate. The funny man also took to Twitter to make an official birth announcement.