A Blue Star is the act of wrapping elastic bands (preferably using heavy-duty industrial sized elastics) around ones penis and testicals tight enough for the testicals to turns blue. Then the testicals are inserted in a female or male's (depending on preference) anus (brown star).
Great for use use during marathon sex sessions when the male (giver) can no longer achieve an erection and anal intercourse is desired. Or in cases where someone has an extremely small penis and anal intercourse is desired, where the female or male (receiver) can not achieve desire from the other partner's penis due to its size.
User warning ... prolonged use can created permanent blue balls or even worse dead balls.
My home-boy Johnny Z. was macking this fat mexican bitch for about six hours and she just kept wanting more and more of his good thing. My muthafucka couldn't get it up anymore so he blue-starred taco-eating bitch.
Johnny eyed up a bunch of ugly Indian bitches and said to his buddies, "Hey what do I care my dick doesn't have eyes. I'll blue star them whores."