What you say when "God damn it" just doesn't suffice-- you need to damn it even harder. First used by Vegeta in Team Four Star's Dragon Ball Z Abridged, it has come to be commonly used to express one's inner torment.
"Oh God damn it Nappa! that's disgusting!"
"Oh God damn it Nappa, no one is going to get that."
"God damn it Nappa"
"But that's impossible-- my transmitter was off the entire time! Whose transmitter could have been . . .