Friction burns are the reason that professional cyclists were those extremely tight shirts all the time. You may have thought it was just a fashion statement but it actually serves a pretty important purpose.
Over the course of a long bike ride a rider's shirt can rub back and forth over a rider's nipples thousands of times. After a while the nipples become irritated and can even bleed. Bikers wear extremely tight shirts so that there will be no room for friction.
This sounds like a silly problem but it can be very painful if riders do not treat it seriously. Those shirts look kind of silly but they can save regular riders a lot of discomfort.