One day some soldiers from a nearby army camp saw a boy leading a donkey.
They thought they would have some fun with him.
“Say, boy, “called out one of the soldiers. “You sure are keeping a tight rein on your brother, aren’t you?”
“Sure am, “said the boy. “If I didn’t he would probably join the Army. “
This joke is included in the Black Book of Jokes. You can order it from here.