here at mizzou, they put condoms over the wireless mic packs to keep out the moisture. every night, the actors arrive, receive their mic pack and a condom over it. a condom for every mic'd person, every night, requires a lot of condoms. we have a 10 gallon bucket full of trojans and durex's, so of course we techies have to play with them.
i've never heard of this practice before i came to mizzou, and i've worked for at least 4 different theatre companies. a lot of the actors said they did this at their high school. odd.
this also results in some very nice images of empty, used condoms backstage and lying on the dressing room floor. you get used to it.