"Man-kini" is a term used to describe a pair of short, tight swimming trunks worn by men. It is a combination of the words "Man" and "Bikini". One could argue that because men don't normally wear a top piece with their underwear that "Man-kini" is a misnomer.
The style of bathing suit in question is more commonly refered as a "speedo". "Man-kini" is generally used as a deragotive label, implying the man in question is effeminate.
A side effect of poor genital hygeine, especially in males. Where the unkempt bush strecthes for hip to hip and basically forms a "hair bikini". Incredibly useful only when you are a member of the polar bears club and love to dive nude into freezing water.
"I got to do something about my mankini, my wife is threatening to cut me off from head if I don't give it a trim."
"I developed those pictures from last night's party, and luckily for Frank, Nick's man-kini was so out of control you can't really tell Frank is getting tea bagged. It looks more like he is getting attacked by a missing link. "
1.
Boy: (waking his mom up) Mommy?
Mom: What is it?
Boy: There's a monster in my closet.
Mom: I thought you already got over your fear of monsters in the closet.
Boy: Yeah, but this one's wearing a mankini.
2. Oh, don't mind that guy, it's just Borat in his mankini.
A one piece t-back style bathing suit which is supported around the shoulders much like suspenders. Seen on gay friendly beaches all over the world. Only to be worn by the most flaaaaaaayming fags. If you are seen wearing a mankini you are the poster boy for gays......some people might call you faggadocious.......some might even say you are starving a for tube steak smothered in underwear or you are training to suck el-dicko. Everyone will see you as a dung punching ass bandit.