Multi personality disorder, or DID dissociative identity disorder, is a mental illness in which the person has 2 or more personalities inside one mind. It is often caused when a child is repeatedly sexually, mentally, or physically abused and cannot physically escape the situation.
1) Dan's daughter was raped so many times when she was very little, she has MPD to cover up the pain.

2) Jeff beat his son so much, he made up more personalities so he could forget the pain.
by IsolatedIncident September 11, 2009
"Oh no! My girlfriend just died! Does anyone have an MPD?"
"Sure, here's my phone. Don't forget to delete the history!"
by B-Raeden January 10, 2012
Multiple Personality Disorder. The act of one user having multiple screennames; esp. for the purpose of being a troll.

Also used to indicate one of said screennames.
"That ass BlackJack is MPDing as Jizz Hitler."
"Yeah, I figured Jizz Hitler had to be an MPD."
by rynne July 1, 2004
Multiple Personality Disorder: An extremely rare mental disorder where a person's mind is split into two or more personalities that attention-desperate teenagers pretend to have so people will think they're unique/cool/troubled/not a loser, etc.
Andy doesn't have MPD, he's just an attention whore.
by Big McHugeLarge December 9, 2008
Hey bob, did you hear Richard was diagnosed with MPD?

That's one small Dick.
by yohabu February 24, 2017
MPD also known as "Malarian Penis Disease" is a sexually transmitted disease, which is usually received when one has sex with skanky girls; specifically ones that "Fat John" has been with.
Jeff-"Hey Mike did you ever get with that chick?"
Mike-"Fuck no! Didn't John get with her? She's probably got MPD."
John-"Fuck you guys.."
by AnOmenofRapture June 2, 2006
Acronym for "Mega Power Dump." Announce or shout this when you are in the midst of toilet warfare.
"INCOMING MPD!!!"

"Dude, do not go in the bathroom. Someone forgot to disarm an MPD."

"I gotta go drop an MPD right now."
by hazedp May 13, 2010