A stragina is a usually a straight, but bi-curious man that hooks up with other guys and likes to wear women's panties and treated like a woman. You typically see these straginas at the redneck bars, hunting, fishing, participating at tea party rallies usually with some homophobic statement sign.
Straight (man) + Vagina(envy) = stragina
Gay 1: What did you do last night?
Gay 2: I went on Craigslist looking for some straight man.
Gay 1: Any luck?
Gay 2: Sorta. I met this married guy who was 6'3, 190, big and butch...but....
Gay 1: But?
Gay 2: It was that guy that beat me up at the bar 4 years ago, he didn't remember me, and as he took of his pants he tells me that he wants to bottom, then I saw his pink lace panties.
Gay 1: OMG, a stragina?!
Gay 2: Yep. I told him to get his stuff and go, I don't need that crap.