Jill complained to Nina, "Rosey told me that you told her the secret I told you not to tell her."
"Well," replied Nina in a hurt tone, "I told her not to tell you I told her."
"Oh dear!" sighed Jill. "Well, don't tell her I told you that she told me."
Two dogs pass a parking meter...
One says to the other, "How do you like that, a pay toilet!"
Why are chemists bad at playing pranks?
They lack the element of surprise.
In days of old, when knights were bold, this particular knight was leaving the castle and called one of his squires. "Here is the key to my treasure chest. I will be gone for about a year and I want you to keep it safe until I return. Don't let anyone near my gold."
The knight sets out on the dusty road, armored from head to toe, and takes a look back at his castle. He sees the squire rushing across the drawbridge, yelling, "Stop! Thank goodness I was able to catch you. This is the wrong key."