My old favorite and one that always sends shivers of hilarity and delight through the hearts of little children the world over:
A Bear and a Rabbit were taking a shit side-by-side in the woods. The Bear asked the Rabbit, "Excuse me, Rabbit, but do you have any problem with shit sticking to your fur?" and the Rabbit answered, "Why, no, Bear, I don't." So the Bear wiped his ass with the Rabbit.