One of the most well-known lines from a movie—"I'll have what she's having."—comes from "When Harry Met Sally". You can watch Meg Ryan doing a great job at faking an orgasm here, in Kat'z Delicatessen (my father's favorite).
Humans are not the only animals who make choices based on what others are having. We now know that dogs will base their decision on what food is the most desirable by watching what we eat. They "recognize human signals about what's good."
In the study about which I'm writing, researchers let dogs choose between two plates, one with a single piece of food and one with six pieces. It wasn't much of a surprise that the dogs preferred the larger amount of good. However, "when a human being showed a clear liking for the smaller plate, the canines likewise went for the skimpier choice. The dogs apparently recognized and responded to the humans' social cues." However, "When the human approached but did not touch the smaller portion, dogs ignored the attention-drawing gesture. For a social signal to influence behavior, it had to demonstrate intention" and the "most effective cues also involved communication, such as looking from the food to the dog and back while talking encouragingly."