First coined by The Monarch in the wildly popular Venture Brothers cartoon, this is a figurative sarcastic list which has events and tasks that are totally lame and simply unwanted.
-Hey little Johnny, can you do me a favor and clean the gutters sometime today?
-Ya, I'll just put it on my to-don't list.
-Oh don't be such a little shit. I'll give you some Fig Newtons afterward!
-Again. Fuck you, mom.
The opposite of a "To-Do List", and isn't literally a list, but just an expression. Normally used when a friend/collleague/person says something that you should do/get and don't agree with. First appeared on the G4 TV Show "Code Monkeys".
Friend: "Hey, you should get that thing for that."
You: "I'm going to put that on my "To-Don't List"."