Is that a threat or a promise?

Used as a snide, defiant rebuff of someone's threat, insult, or verbal attack, as if what the other person is saying might actually be enjoyable. A: "I suggest you learn your manners. The next time I catch you here, I won't be nearly so forgiving." B: "Oh, Mr. Livingston, you tease—is that a threat or a promise?" A: "Look at what you did! Screw you, pal!" B: "Is that a threat or a promise, pretty boy?" A: "Don't worry, I'll be back later." B: "Now, is that a threat or a promise?"

threat or a promise, is that a

Are you giving me bad news or good? According to lexicographer Eric Partridge, this was the soldier’s answer to the vulgar phrase, “Fuck you!” and dates from World War I or even earlier. In civilian language it came to be applied other than sexually, whenever a doubtful proposition was made. Partridge quoted Julian Symons’s A Three Pipe Problem (1975): “‘Goodbye, I advise you to keep out of my way.’ . . . She smelt of cigarette smoke and gin. ‘Next time, Mr. Holmes? Is that a threat or a promise?’”