Do you say anything?
The trouble is, I was exercising, and I would have had to stop, go and interrupt the other person's exercising, and explain the issue of which they may not have been aware. I did not want to stop, so I did nothing. Also, what if the person knew, and didn't care? Then again, what if the person did care, in fact really did not want everyone to know their underwear preferences?
What do you think?