Neil Patrick Harris Tweets Babies, Gets John Lithgow As 'How I Met Your Mother' Dad

Neil Patrick Harris certainly has a lot going on with his family these days -- both on and off screen.

The multi-talented funnyman, who in October with his partner David Burtka welcomed baby twins via surrogate mother, tweeted about his best audience: his kids.

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

That's not the only family news for NPH: it was announced last week that actor John Lithgow will play his character Barney Stinson's dad in a late February episode of 'How I Met Your Mother.'