Waxing wroth

Is there such a phrase as "waxing roth" --- meaning, I think, to be very upset or mad?

I recall that phrase was included in a Marx Brothers movie, the one where Groucho is president of a university. He's in his office and in comes his secretary; the secretary reminds him that an important visitor has been waiting very long to see Groucho and that the latter has kept the visitor waiting.

The secretary says, "(the visitor) is so upset at being kept waiting -- he's waxing roth." Groucho, as only he could do, quips, "Well tell him to wax someone else!"

You were close. It's spelled wroth.

For your further enlightenment: "Waxing" means "becoming" or "growing," as in "a waxing moon," one that (apparently) gets bigger. "Wroth" is an archaic word for "wrathful." ~rb