I was flying to the Pacific Northwest to visit friends. Alice was two. So still small (about 16 lbs.).

No issues at the airport, no red flags at security, nothing but net. I get on the plane.

Halfway to my destination, I finish my book and get up to get a new one from my suitcase.

The suitcase meows at me.
Alice pops her head out.
Uh.
Crap.

I flag down a flight attendant. "I have a cat."
"I have a dog. Please sit down."
"Meow," says Alice.
"Uh," says the flight attendant.

Alice had REMOVED MOST OF THE CLOTHING from my bag, crawled under what was left, curled up, and gone to sleep.

I had to hold her for the rest of the flight. She thought this was the best idea ever.

I had to buy new clothes AND a cat carrier AND a pet ticket to get her home. And I will never have faith in the TSA again. (Not that I had a lot of faith to begin with, but there's "this is security theater" and then there's "YOU MISSED THE LIVE CAT.")