Carry on with what you are doing - it will give me an excuse to behave badly.

This line was made famous by the Clint Eastwood character Inspector (Dirty) Harry Callahan in the 1983 film Sudden Impact - the fourth film of the Dirty Harry series. Callahan encouraged felons to commit crimes so that he would have an excuse to shoot them. In Sudden Impact he dares a crook to shoot his hostage with the line "Go on punk, make my day".

Dirty Harry wasn't the first to use the phrase with that meaning though. It had been spoken earlier by the character Tom Walsh - played by Gary Swanson in the film Vice Squad (1982). In that film the line was, "Go ahead scumbag, make my day".