The opening of a variable catchphrase originating in the satirical weekly Private Eye and now widely recognized in Britain. It was the editor's intervention to stop a list that had gone on too long and become too silly.

I haven't any examples to hand, but it's in this sort of context. On Everything2 you might be able to find nodes for spider monkey, colobus monkey, Sumatran bird-eating monkey, giant lesbian monkey, Venezuelan lesser crested soy-nesting monkey (That's enough monkeys. - Ed.)