Usually an attractive woman or girl present in geeky places and conferences to attract the attention of a geek
. You can find them in places where you would last expect to find so many attractive women - career fairs at linux conferences, linux meetings/conferences.
They usually have a see-through bra, dress with nipples poking out or low cut cleavage dresses aimed to attract the virgin (talented and hardworking) geek.
Tom: Man, those chicks at Linuxworld in SF were so f**king hot, i didn't know chicks who dressed like that are into geeky stuff like i am.
Matt: You idiot, those were geekbait