"Have you ever had sex with any men or boys? Did you ever masturbate with a man -- let him suck your dick -- or whatever? You look like you might like that."
"No! Never! Absolutely not!" he replied with pained righteousness. "I admit that ... well, that I haven't been ... well, very confident around girls ... uh, around women, but I've *never* been interested in men at all. Never!"
I could tell that he was telling the truth. He was just a shy, insecure straight guy for whom women had been totally inaccessible except as people to watch and fantasize about.