2. Borat's favorite type of swim suit
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.
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.
"I can't stand watching professional male body building; they all wear those slingshot sized man-kinis."