WTF is a wahwah brush?

Factual Questions
1

In a movie titled All I Wanna Do (1998, set in the early 1960s) some of the girls start using the phrase “up your ziggy with a wahwah brush”. Until tonight I assumed that it was a nonesense phrase made up for the movie. Then in an episode of Bewitched (2x37 “The Girl With the Golden Nose”, 1966, 9:17 into the episode) Darrin is trying to lose an account by being obnoxious. During a long stream of babbling he says “I mean, it’s hey you kids with a wahwah brush”.

I googled “wawa brush”/“wawa brush” and almost everything is a reference to All I Wanna Do but there is also a clip of Jack Nicholson using the phrase “up your giggy with a wahwah brush” in the movie The Last Detail (1973, apparently set around that time).

So, what can you tell me about the phrase. Origin? Widespread usage?

2

Urban dictionary says a brush for pubic hair.

3

It’s a term that broke Google’s AI Overview feature.

A Wawa brush is a sticker featuring Gabby Hoffman as Odette Sinclair in the movie The Hairy Bird. The sticker is designed and sold by rachaelthegreat.

4

I don’t know if this is the right answer but Wawa Zainal’s company Wawa sells beauty products including brushes.