It's time for the annual holiday binge of office parties, neighborhood gatherings and cocktail hours. Not to be a downer, but health-conscious fun-lovers should be wary — and not just of gaining weight from all those extra calories.

We're talking, of course, about double-dipping. Turns out that science backs the popular fear that partygoers are sharing more than good cheer when they go back to the communal bowl of dip for seconds with the same chip.

Here's what you should consider before you bite:

It's really that bad: Food science students at Clemson University examined the effects of double-dipping using volunteers, wheat crackers and several sample dips. They found that three to six double dips in one bowl transferred about 10,000 bacteria from the eaters' mouths to the remaining dip. That means if you're at a party and three to six people double-dip their chips, any chip you dip may pick up at least 50 to 100 bacteria. The research was published earlier this year online in the Journal of Food Safety.

Will it make you ill? Maybe. It depends on how much bacteria you pick up, how many people are double-dipping and what kind of bacteria they have in their mouths.

Pick thick: In general, thicker sauces — cheese dip, chocolate syrup, hummus — may be safer. They have less bacteria and the number of bacteria in them gets smaller over time, the Clemson study found. Salsa picked up the most bacteria, probably because it was runny, making it easier for bacteria to slip off the chip back into the bowl.

TV imitates life: Clemson professor Paul L. Dawson and his students were inspired to test the double-dip theory by a rerun of a 1993 "Seinfeld" episode in which George Costanza is confronted at a funeral reception by his girlfriend's brother after he dips the same chip twice. The scene, which ends with the two men wrestling for the chip, is credited as the first popular reference to the social taboo of "double-dipping."

The solution: Serve small, one-dip chips or only munch with people you "really" like.

When double-dipping runs amok it's "like kissing everybody at the party," Dawson says.

Distributed by McClatchy-Tribune Information Services.