The end result of watching a 'last episode' of any TV serial written by Steven Moffat, owing to the impossibility, confusion and pure anger at very complex and brilliant plots. Especially when there is a sizeable gap between one episode and the next. Usually found in relation to British Television shows Sherlock and Doctor Who.
A: Did you see that episode last night? It was infuriating!
B: I know! My head's been totally moffucked!