I've got a bad one.

I went to peru for two weeks to visit my girlfriend while she was interning at a clinic there.

I asked one of my gf's friends to pet-sit.

When I came back, I found out she had left the top open accidently one night.

My bp is still missing, even after trying every trick in the book

Two lessons:
1) don't let anyone watch my snakes while I'm gone, just lock the cage top.
2) escape proof cages are only escape proof as long as they are operated correctly.