Researchers from the University of Chicago wanted to test whether eating exactly the same food could heighten the rapport between two people. They ran a series of three experiments to find this out.
There were 176 participants in the first experiment. They did not know each other and were paired up to play an economic game. One of them played the role of an investor and the other pretended to be a fund manager. Some pairs ate the same candies before the game, while others ate different candies.
In those pairs, where people ate the same candy, they gave more money to their counterparts, while those who ate different candies were less trusting and generous with their funds.
More details here.