This was published on the groaners listserv. The author is not known.

Once upon a time, there lived in an African forest, two families of amicable, hardworking wildebeests, who often enjoyed picnicking together. However, each family had one young mischief-maker, though each mother was convinced that her own little child was innocent and that the other was the troublemaker.

“You should punish that rascally brat of yours,” shrilled one of the mothers, finally. “A sound spanking might do him some good.”

“Spank my son, indeed,” huffed the other. “Why don’t you go paddle your own gnu?”