Adapted from a post on Torahmusings.com
There was a 1993 episode of the television sit-com Seinfeld that focused on a specific area of hygiene and entered a phrase into the common lexicon. It is now common to hear people speak of "double-dipping" and its lack of social acceptability.
Here is a transcript of that brief Seinfeldian exchange:
[George, attending a wake, takes a large tortilla chip, dips it into a bowl of what appears to be sour cream, takes a bite, dips it into the bowl again, and then eats the remainder of the chip.]
Timmy: What are you doing?
George Costanza: What?
Timmy: Did, did you just double dip that chip?
George Costanza: Excuse me?
Timmy: You double dipped a chip!
George Costanza: Double dipped? What, what, what are you talking about?
Timmy: You dipped a chip. You took a bite. And you dipped again.
George Costanza: So?
Timmy: That's like putting your whole mouth right in the dip. From now on, when you take a chip, just take one dip and end it.
Timmy is teaching George a very important lesson about personal hygiene and concern for fellow eaters. There is an interesting parallel in a Talmudic passage that makes the same point in a somewhat humorous manner.
Rabbi Yossi and Rabbi Yehudah [were eating from the same bowl]. One was eating porridge with his hands and the other with [a utensil fashioned out of] tree bark. The one eating with bark said to the one eating with his hands: "Until when will you keep feeding me your excrement?" The one eating with his hands said to the one eating with bark: "Until when will you keep feeding me your saliva?" [Babylonian Talmud, Nedarim 49b]
These two rabbis were eating from the same bowl and double dipping. One pointed out to the other that his hands were dirty, jokingly referring to them as being full of excrement. The other retorted that every time he double dipped, he was putting his saliva back in. Who needs Seinfeld when you've got the Talmud? As the great Talmudic sage Ben Bag Bag said about the corpus of Jewish writings, "Turn its pages, turn its pages! Everything is contained within it.” Even the lesson on double dipping.