It may look like the seagull is playing along with the man hiding the food under three cups in an attempt to trick the bird, but know this: seagulls are motherfuckers who don’t care about you or silly games. It is not playing along. It is in complete control.
The bird is only pretending because it knows that it’s the only way it’ll get food from this guy (for now). Once the guy exposes his food stash, the seagull is going to attack it and then poop all over the dude who thought it was cute to play games with seagulls.
Those feathers are hiding its contempt for all humans.