What word or phrase does your mother always say?
1620s, "fit of ill humor," perhaps imitative of an exclamation of disgust (cf. German muffen "to sulk").
1797, "to take offense at;" 1811, "to put out of humor," from miff (n.). Related: miffed; miffing.
To anger; offend: The way I came on to you the other night; I thought you'd be miffed (1811+)