1. A subtle, yet sarcastic promise to do something that will most likely never happen.
2. An unspecified time in the future that will never arrive.
3. Probably never, but for some reason, you still have hope.
"Sure, I'll help you with that project tonever, just as soon as pigs start flying out of my ass."
"I can have your money for you tonever, I just gotta call my friend and then..."
"When do you think you'll get that raise?" "I don't know, probably tonever at this rate."