Donald Trump is making good on a vow to sue HBO talker Bill Maher for cranky comments the progressive comic made last month.

Maher quipped on The Tonight Show with Jay Leno that he would give $5 million to charity if Trump could prove he wasn't the "spawn of his mother having sex with an orangutan."

Har har.

Trump didn't take the comment, meant to mock Trump's Birther charge against President Barack Obama, well. Now, the real estate mogul is using his Twitter account to let the world know he indeed is suing Maher to force him to make good on his charitable promise.