I was skateboarding in an empty paring garage once and for some reason the fire alarm came on. There's a decent echo in there and the lack of cars made it that much more brutally loud.
Obviously, certain heavy metal shows were similarly loud. One avant garde show I went to, the guy was making music with brain waves that were attached to someone's head. It was so loud it actually melted the PA or something. https://www.youtube.com/watch?v=XI4Mge8nLMw
( trivia: I saw the bass player of Galaxie 500 walk out and called her a sellout for doing so)
When I was a kid, I tried putting a 200w lightbulb in my room light...
One day, it shorted out...
When I lived in Wappinger Falls, NY in 1967 I heard a sonic boom from a jet. Freaked me the f**k out.
In 2015 I had just come home from work and it was raining, thunder, lightning, the whole works. About half an hour after I got home, I heard what sounded like a blast but I thought it was just the lightning but a few minutes later my neighbor called to say that a thatched roof house up the road from us had been hit by a lightning bolt, the bolt struck the mains, the place caught fire and later burned to the ground 😳😳😳😳
I once heard the military detonate a bomb on a hilltop at night and it was so loud it felt like getting punched all across my body at once, and left my ears ringing for hours. Nothing else I've heard, even a nearby lightning strike, (the holder of the number two spot) comes remotely close.
When I first checked onboard USS Lockwood, the berthing compartment I was assigned was almost directly underneath the ship's 5 inch forward gun. Try sleeping through a gunnery exercise sometime! Not only was it deafening, but the whole ship lurched with the recoil every time it fired.
^There's a military base a couple counties over that recently started battery drills... Not "loud" at this distance (considering), but annoying enough...^
Either the town's tornado siren going off during band practice in middle school right when we were marching by it (1997 or 1998) or lightning striking a tree in a neighbor's yard a few years ago