Charlie Sheen -- I Was JOKING About Porn Star Marriage ... To Stroke Out My Ex-Wife

Charlie Sheen did NOT actually tie the knot with his ex-porn star GF Brett Rossi over the weekend -- despite tweeting he did -- Sheen tells TMZ, he was just joking ... in a humorous attempt to incapacitate his ex-wife.

The Warlock sent the tweet Sunday from Iceland, including the photo, saying, "This is the house ware M Gorbachev R Reagan did some epic. it's also where S and I GOT MARRIED!"

But Sheen tells us, the tweet was all in jest ... "I wanted to give Denise [Richards] a stroke!!!"

As we reported, relations have been strained between Charlie and Denise recently. Charlie accused Denise of refusing to allow their daughters to open Christmas gifts at his house over the holidays, calling her a heartless ugly hag. Denise denied the accusation.

But not all of Charlie's recent tweets were a joke -- we're told the forearm tattoo he dedicated to Brett and his children is 100% real. Each letter stands for one of Charlie's children: Max, Lola, Bob, Cassandra, Sam, and Denise's adopted daughter Eloise. The safety pin symbolizes Brett.