look up any word, like ratchet:
 
1.
Lit. 'Playing on the Jew', this is a German term denoting either:
1. manual masturbation of the clitoris, by the female herself or her partner; or
2. cunnilingus.

Here 'Jude' or 'Jew' is a humourous Germanic term meaning 'clit', alluding to the smaller average size of the Oriental Semitic Penis as compared to the Germanic North European Penis. Essentially, this term is based on the Jewish Small Penis Stereotype, which is a subtype of the Asian Small Penis Stereotype.

Christina von Braun describes the first meaning: 'Im Wiener Slang der Jahrhundertwende war „Jud“ ein gebräuchlicher Ausdruck für die Klitoris, und weibliche Masturbation wurde „mit dem Juden spielen“ genannt.' - 'Ist die Sexualwissenschaft eine „jüdische Wissenschaft“?' In: 'Durch Wissenschaft zur Gerechtigkeit?: Textsammlung zur kritischen Rezeption des Schaffens von Magnus Hirschfeld' Hrsg. Ed. Andreas Seeck. Berlin: LIT Verlag, 2003, p 233-252: 236.

Meanwhile, K Reiskel records the second meaning of either irrumation or fellation of the clitoris: "Jud, der, Klitoris. Redensart: Am Jud'n spiel'n. Den Jud'n stemma, fellare vel irrumare clitorem." - 'Idioticon Viennense eroticum' K Reiskel. Anthropophyteia {Deutsche Verlagaktiengesellschaft} Vol II (1905) p 1f: p 9.

To be distinguished from 'Am Juden stemmen', which connotes exclusively cunnilingus.
1) As Dr Leo Kanner observes, 'Am Juden spielen' is recorded from all parts of the Germanic world, right from Berlin to Austria & Styria:

"Der Jud seems to be a common name for the clitoris in different parts of the German-speaking sections of Central Europe. Kostial (14) heard it used in Styria. Reiskel (15, 16) found it in Berlin, where he also met the expression Jude Kohn, & in Vienna, where Am Jud'n spiel'n and Den Jud'n stemma was used to mean 'fellare vel irrumare clitorem'.
{14. Kostial, J: Steirisches erotisch-skatologisches Idiotikon. Anthropophyteia. Vol VII, p 22.
15. Reiskel, K: Idioticon Viennense eroticum, Ibid, Vol. II, p. 9.
16. Reiskel, K: Eine Auslese von erotischen Wörtern und Kraftausdrücken der Berliner Mundart. Ibid, Vol II, p 21.}"
- 'A Philological Note on Sex Organ Nomenclature' Leo Kanner, M D. Psychoanalytic Quarterly 14 (1945) 228-233: 231.

2) Hans: Weil Ich einen Judenpimmel habe, muß Ich immer meiner Frau am Juden spielen! (Because I have a Yid dick, I have to always play on the clitoris for my wife!)

3) Dame Klembitz: Kannst Due mir am Juden spielen? (Can you lick or fondle my clit?)

4) Jens: Jede Nacht kann Ich hören, wie meine Schwester am Juden spielt. (Each night I can hear my sister flick her rose-bud)
by Moollah_Do_Pyaza October 07, 2012