Anything that looked like a good idea at the time, but has become a quagmire from which you cannot retreat gracefully.
A relationship that is unpleasant but can't be dropped.
An unsolvable problem or bad situation you should have backed out of a long time ago.
I thought my boss would appreciate this new project, but it's Viet Nam.
"I thought you were getting along with your brother now?"
That party was Viet Nam.
When you're so stressed out you forget things, blame it on other people, and otherwise act like you've lost a major portion of your cognitive abilities.
I'm sorry I went home with your jacket last night and mistook it for my roommate's this morning. It's the Stressheimer's.