Has happened to me numerous times. Usually when I have headed on after an evening out in civilised circumstances while on a night out. On thse occassions I have been like you not going regimental. Usually it is the women who do so drunkenly, even when out in gay bars.

When they looked disappointed that I am wearing underwear, I just say, "Sorry, but it is people like you that make we feel safer going this way. I don't want to get arrested for indecency because of your actions."

It has never happened to me on the street or in a normal setting though only where alcohol is being consumed.