Pretty much everyone in my building last year knew. I've posted about it before, but I was always asked to show it at parties, so there was no secret.
But one of my favorite things to do could be useful in your situation: no underwear with basketball shorts. Lighter colors work better. It's like when a girl wears a white shirt with no bra; molds right around it, but lets everything swing when you walk. I used to love going into a room where a group of girls would be studying and seeing all of their eyes glued to the outline. Sometimes I'd shift my weight back and forth between my feet so they could see it sway.
Try it once and you'll know if that's the sort of thing they're interested in. But if they don't respond, I wouldn't push it any further. There's a fine line between advertising and harassing.