It comes from American prison culture meaning you were available to be ****ed by another guy. If half the dopey kids knew this they wouldn't be long pulling up their pants, the other half wouldn't as they're just gay anyway.
That explains a lot, ta for that hash, most of the wee little ****'s around here look more efeminate than the burds. Dozy little **** stabbers. Still, i suppose the more efeminate queens there are around here the more rampant gaggin fer it teen clunge there is for the real men. **** i'm starting to sound like a dity old man.