What is the strangest damage to an aircraft that you have ever seen?

Weirdest I remember was when CND Campaign for Nuclear Disarmament in England snuck onto base and dumped a butt load of Blood Red Paint on an Aircraft.

Lots of bird strikes. Seagulls and Pelicans.

An F-111 that had (ok, this was in 1974-sh, so this is from long-ago memory) a goose hit the (I believe) left side windshield. Don't recall any injuries, probably were some. That was in my first few months, so nobody really gave me any details, I was an AIC. Other than that, as an NCO and senior NCO, picked up or was present at (one was lost at sea) 5 F111 crashes. I won't put the location here in case relatives see, but one in particular was a god-awful mess where the AC apparently flew almost straight down into the ground and a flock of sheep at close to Mach 1. Pilots didn't get out. I guess they thought they were in cloud but it was fog instead? No clue why, really. There were no repairs, but they would have been extensive and probably still ongoing. This was in the 1980's.

While stationed in Germany, got called out when a C-5 ran its T tail into the vert of a civilian 747. Tore a 1/4 off the T-tail and half way through the vert.

Well, there was that one time that a B-52 lost its entire vertical stabilizer, forcing the crew to make an emergency landing.

https://www.popularmechanics.com/military/aviation/news/a27584/b-52-landed-without-a-tail-fin/

Blown apart from Rockets & Mortars / shot full of holes from ground fire

Ive seen white a few of them since as rotary we deal with some awkward landing areas.

1. AH-64 lands on tree stump ripping Doppler faring, mount, and antenna off
2. CH-47 landing on raised platform comes in too low and strikes platform (Concrete) cracking several formers in the floor
3. UH-60 called forward due to a small ditch in LZ landing on a small COP at night (under NVGS) and rotor blades strike T-walls taking 4feet off the rotor blades
4. UH-60 landing on a jersey barrier buckling most of the tail
5. RPG struck stabilator of AH-64 and found on post flight inspection lodged in fairing below #2 engine
6. UH-60 attempts dust landing at night way too hot and pancakes on the ground. When returns to the FOB you can see all the sheetmetal looking like crumpled and flattened Tin-foil

And of course plenty of Small Arms holes

Lightning strike just behind pilots cabin on flight from Panama to San Antonio.......Can you imagine what those pilots were thinking......I'm still here, so they did a good job!

I forgot two f-15 stories. When I was in Korea, 83-83, we heard about an f-15 coming in with no nose gear. So, I ran over to watch this pilot bring it in. He came down on both mains and rose it out to almost the end of the runway. The nose was starting to come down and then he punched. Slammed the nose into the ground. The aircraft quickly came to holt. I was just glad I was not working flight-line in Korea and had to deal with that, but it was cool to watch.

When I was in Saudi Arabia, I had to go over to McDonald Douglas to get a part for an f-15. Inside they had an f-15 on jigs. The Mechanic told me a Saudi pilot had punched because one of our female air traffic controllers had responded to his call. Really? If that wasn't astonishing enough, they were rebuilding that aircraft. I'm a sheetmetal guy thinking, you gotta be kidding me.

I watched a B-52 come in with the flap hanging from one actuator. How that thing was still hanging on is beyond me. Amazingly the surrounding damage was as bad as I had expected.
We also had to have depot come in and repair the nose of a B-52 that had been hit by five geese. We assisted on this repair.