A "
thank you" given to someone for a favor or action that has not yet taken place and never ends up materializing.
You have already thanked them for
something they did
not really do. It is not fair and can be taken back at any moment.
Yesterday my wife said she was going to
give me a message when we got home from work so I said "thanks, I really
appreciate that". We got home, she ate dinner and went to bed with no message yet had already received her thanksism. I woke her up and took it back.