In a past life I had borderline crazy downstairs neighbours. They would usually wake us up by screaming at one another but on this particular occasion the radio was blasting at a ridiculous level. I actually don't think they home and perhaps it was an alarm set on the radio which had turned it on.

Thankfully after about 30 minutes of my flatmate and I getting really pissed off (it was like in the same room loud, not just a minor annoyance) I remembered that I had an old car FM transmitter for an MP3 player, after borrowing the batteries from the TV remote, cycling through the stations I was overjoyed to discover that one of the stations was close enough to the radio frequency to blot out the station it was tuned to. The reason I think they weren't home is I turned it on and off a few times but they didn't attempt to turn the radio to another channel or anything like that. I went to sleep with it on.

Technically the FM transmitter was legal at that point but using it to deliberately block someone else's radio is almost definitely illegal.