To be "shenned" is to have a harmless practical joke played on you. In this case, when dining out, your friends are free to pull "shenanigans" on your food, drink or personal property when you leave the table for any reason.

Examples of being shenned include hiding sugar packets/straw wrappers/napkins in coat pockets, mixing a bit of salt into a soft drink, or hiding a tea bag in one's chicken lo mein (that happened to me personally).

The only way to counter shenanigans is to declare "No shens" to your dinner party when leaving the table. Only then are you safe from being shenned.