BAD MOON RISING
Lycra has a lifespan, especially when stretched. The simple first rule of fright club is to tell your buddy with the seethrough pants why you’re uncomfortable riding behind him. If nothing else, it will make for merriment for the rest of the ride; and if nobody tells you, it’s unlikely you’ll ever know.
This applies to complete strangers, too (just with less mickey-taking). For the common good, there should be no shyness here. Speak up, or forever hold down your breakfast.