It really depends on the girl. If your girl gets regular manicures, gets her hair done, and tends to look super put together—then she probably values a suave partner, and, yeah, I’d be on top of your underwear game.
So, rule No. 1: No tighty-whities. Ever. Unless you know she has a thing for briefs, wearing them will freak her out because it’s a sign your mom still buys your underwear for you. Boxersare OK, but boxer briefs are really your best option for looking like a put-together guy.
Now, fabric-wise: Go cotton, or at least mostly cotton. Shiny, synthetic-looking materials not only look skeevy, they can also make you smell a little ripe—which probably isn’t what you’re going for. Colors are fine, but nothing too bright or too patterned—Hawaiian shirts have their time and place, but it’s not in your pants during a date.