Steal some clothes.

You see only one piece of clothing nearby, hanging on a clothesline by somebody's house. Unfortunately for you, it appears to be nothing but a string attached to two pieces of fabric likely not more than an inch or two in diameter. But, it's better than nothing. You've seen girls walk around in tiny bikinis before. It's summer. Surely nobody would care that much if you wore one on the street, as long as nobody noticed your skirt problem as well.

You sneak into the yard and yank it free. You wrap it around your torso, and it thankfully fits. The bits of fabric just barely cover your nipples, but your hands are now free to grip your skirt's bottom if the need arises. You can (semi-)comfortably find somewhere else to be now.

You walk. You grow a little embarrassed knowing your barely covered breasts are bouncing in the open, but it distracts at least from your lack of underwear.

The odd person eyes you up and down. You feel a little complimented, really. It's not easy to keep a kind of fit body.

You know that Troy's house is nearby. You always thought he was so handsome and nice, but never made the move to be more than just friends. That being said, he would never make fun of you for your situation and could give you a ride home.