Living in a country area, I quite often do gigs in farm buildings, barns/silage sheds/cowsheds. I once did one job for the young farmers club, stood on a 40ft trailer and over the wall behind me were a herd of cows, not at all bothered about the noise.
I have also worked for the MoD in an army camp just down the road. Normally in either the officers or sergeants mess, occasionally in the canteen, and once on a helicopter landing pad.
but
The strangest place I have ever DJ'ed is probably in a fire station, and halfway through the gig there was a call out, so that was different