1) You've returned home and had to remove condoms, gaff tape, a couple mic clips, and a few patch cables to get to your keys.
2) You were puzzled by the shock of everyone around you as you pulled those items out of your pockets/bag.
3) You grit your teeth every time you hear high frequency feedback.
4) You've been questioned by campus authorities as to why you were hanging around a hallway dropping different pens for 2 hours.
5) You build a soundscape in your head every morning on the bus because the engine sounds cool.