I accidentally brought a compressed air horn through once (flammable liquid). Forgot it in my bag after going to a sporting event.

I'm sorry, I know it's wrong, but I'm laughing so hard right now thinking about blowing an air horn in the confines of a plane.

Not TSA, but the only time I've ever had anything confiscated was flying from Japan to NZ. They took my ~$15 pocket knife with it's 2.5 inch blade. But it turned out they gave it to the crew in a sealed bag because I got it back at the end of the flight. They did not however, once they'd confirmed the export paperwork was fine, do anything about the custom made ~$5000 iaido sword that I was carrying. So, 2.5 inch mostly blunt pocket knife, bad. ~4 foot razor sharp sword, perfectly fine.

I love Japan. :)

I collect coke bottles from all countries I visit. I had a bottle off coke that made it from Ecuador to Atlanta and home. On my next trip the water bottle I forgot about was taken in Atlanta

Ironic. ;)

Managed to get through with a half full Nalgene bottle about a year ago. Clerks must have been distracted by their workplace gossip while running the x-ray.

Earlier this year, I got back home and realized there were a couple live rounds in my bag. Had taken it to the range a week or two earlier- rounds had gotten stuck in a pocket at the bottom of the bag.

Just in case you get a secondary screening? :D

+1. I have two quart bags, never removed them, never been asked to. With pre-check it's now a non-issue.

That's a CPB issue, not a TSA issue, no?

Probably. The TSA seem to think that everything's their business though.

Ammunition mainly. Did get stopped for some flash bangs that were training versions, but they didn't seem to care. They did all take a step back when I yanked the pin to show them it wasn't going to actually go off.

I don't think they're legal anyway--fake weapons are treated as real.

Paint pens containing solvents. I think they were TSA illegal. They certainly weren't in my liquid bag.

The wife wisely removed the Sig Sauer from her purse. She neglected to take out the spare mag full of ammo however, and apparently they either missed it or didnt care.

Hmmm, can't think of anything in particular. Although after my switchblade style car key got a bit of extra scrutiny from TSA agents a few times, I feel like it's a victory now when I sufficiently hide my keys in my laptop bag and they don't see them.

Would definitely be hilarious if the suitcase shifted in the overhead turing takeoff or landing and the button got pushed down.