In my home town in Montana, junior high and high school car washes were a big thing. You'd see three or four of them every week during the summer. Not once did a boy take his shirt off, or wear a Speedo.
When I got to college, I made a friend, Rich, who was from Los Angeles. Rich told me that guys in nothing but Speedos were the norm at high school car washes. They were all straight, he said, but the guys had a freedom of body and sexuality that made my home town look like an Amish settlement.