I was calling a dance at the Metropole Hotel in Brighton (yes, that one) and using my radio mic. Suddenly my voice went incredibly loud and we had not touched the PA. However much we turned it down the mic could be heard throughout that floor of the hotel. It took us a while to realise that the loud sound was not coming through our PA but from the disco speakers that were to follow us. Disco had set up his gear and then put in on a timer and his radio mic must have been on the same frequency as mine. We unplugged his gear at the wall and carried on and managed to recover the excellent atmosphere that we had created earlier.
When Mr. Disco returned, he wanted to know angrily who had unplugged it and when we told him it was us and asked why he had put his equipment on a timer - it had nearly ruined our part of the evening, He said that he needed to warm his equipment up. One of the band told him to stop talking bollocks, but he continued to rant at us. It was a posh do with an event organiser and she came up to ask what was going on. She had been there when the huge increase in volume has happened. First she apologised to us than told the disco bloke what she thought of him in no uncertain terms. He stomped out of the room in a huff.
The disco was scheduled to follow our dance smoothly and straight away. By the time we has packed up and were ready to leave, he hadn't returned.