Green’s Dictionary of Slang

1. (US) sexual intercourse; sexual play.

1986		P.W. Kaplan Single States 18: [A]sking of God only that tnight they might make moofky-poofky with a junior partner’.
1997		D. Greenburg Moses Supposes 53: Potiphar’s wife gazed upon Josph’s many physique and was highly desirous of making moofkie-foofkie with him.
2007		E. Flint (ed.) Best of Jim Baen’s Universe n.p: ‘[A]lready you’re making moofkie-foofkie in an alley with this piece of work. What are you [...] Little Miss Round Heels?’.
205		R. Lobis Coming of Age ‘ [ebook] ‘I don’t think she trusted me not to indulge in a little moofky-poofky’.

2. oral intercourse, whether fellatio or cunnilingus.

1996

T. Janowitz By the Shores of Gitchee Gumee (1998) 215: ‘A moofty-poofty is where a man — or a woman but more frequently a man — takes the mashie niblick of another man and, putting it in his coral seas, sucks on it’.