On the scientific front, an article in the New York Times reports that a group of researchers at Clemson University have determined that double dipping your chip at a party does indeed spread bacteria. The report will appear later this year in the Journal of Food Safety.
A group of undergraduate students under the supervision of Prof. Paul L. Dawson were following up on the Seinfeld episode in which George Costanza double dips his chip at a funeral reception. George is confronted by Timmy who is appalled at George’s recklessness.

The students did a controlled study of dipping crackers into several different foods - water, salsa, cheese, and chocolate - and determine that a significant amount of bacteria is left behind in the dip. This is especially true for “runnier” liquids like the salsa, whereas the thicker foods stick to the chip and leave less stuff behind.

So, next time you are at a party, be careful with that chip. Double dipping really is yucky.