Nothing is sadder than a primate behind glass being reduced to ask wandering passersby to help it escape from its hell hole. Filmed at a welsh mountain zoo, this chimpanzee seems to be indicating to the visitor to help him unfasten the bolts:

Either this chimp is desperate or it just wants to be let out so that it can beat the crap out of the guy taunting him from the other side. But according to YouTube commentors, the chimp was actually using sign-language to request for the crackers strewn around his compound. So guess we now know which of these two is the real dumb animal here.