Commissioned by a zoo to bring them some baboons, the big game hunter devised a novel scheme to trap them - his only requirements being a sack, a gun, and a particularly vicious and bad tempered dog. Once in the jungle he explained to his assistant, "I'll climb this tree and shake the branches; if there are any baboons up there, they will fall to the ground - and the dogs will bite their tail and immobilise them so that you can pick them up quite safely and put them in the sack." "But what do I need the gun for?" asked the assisant. "If I should fall out of the tree by mistake, shoot the dog."

Last I heard this one the dog was to bite the testicles

Foriegn dog BAW.