What word or phrase does your mother always say?
Old English wulf, from Proto-Germanic *wulfaz (cf. Old Saxon wulf, Old Norse ulfr, Old Frisian, Dutch, Old High German, German wolf, Gothic wulfs), from PIE *wlqwos/*lukwos, from root *wlp-/*lup- (cf. Sanskrit vrkas, Avestan vehrka-; Albanian ulk; Old Church Slavonic vluku; Russian volcica; Lithuanian vilkas "wolf;" Old Persian Varkana- "Hyrcania," district southeast of the Caspian Sea, literally "wolf-land;" probably also Greek lykos, Latin lupus).
This manne can litle skyl ... to saue himself harmlesse from the perilous accidentes of this world, keping ye wulf from the doore (as they cal it). ["The Institution of a Gentleman," 1555]Wolves as a symbol of lust are ancient, e.g. Roman slang lupa "whore," literally "she-wolf" (preserved in Spanish loba, Italian lupa, French louve). The equation of "wolf" and "prostitute, sexually voracious female" persisted into 12c., but by Elizabethan times wolves had become primarily symbolic of male lust. The specific use of wolf for "sexually aggressive male" first recorded 1847; wolf-whistle first attested 1952. The image of a wolf in sheep's skin is attested from c.1400. See here for a discussion of "wolf" in Indo-European history.
"eat like a wolf," 1862, from wolf (n.). Related: Wolfed; wolfing.
Figuratively, anyone who disguises a ruthless nature through an outward show of innocence. Jesus taught his followers to “beware of false prophets, which come to you in sheep's clothing, but inwardly they are ravening wolves.”
Heb. zeeb, frequently referred to in Scripture as an emblem of treachery and cruelty. Jacob's prophecy, "Benjamin shall ravin as a wolf" (Gen. 49:27), represents the warlike character of that tribe (see Judg. 19-21). Isaiah represents the peace of Messiah's kingdom by the words, "The wolf also shall dwell with the lamb" (Isa. 11:6). The habits of the wolf are described in Jer. 5:6; Hab. 1:8; Zeph. 3:3; Ezek. 22:27; Matt. 7:15; 10:16; Acts 20:29. Wolves are still sometimes found in Palestine, and are the dread of shepherds, as of old.