This was too funny:
At Northern Ireland's Belfast Zoo in September, Phoebe the chimp and two others managed to climb out of their compound, and armed security guards had to come round them up. In an effort to frighten the animals into submission, they fired shots into the air, and according to the reporter for The Guardian newspaper, the chimps not only became docile at the sound of gunfire, but they put their hands up. [The Guardian (London), 9-8-05]