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."
A minister who was very fond of pure, hot horseradish always kept a bottle of it on his dining room table. Once, at dinner, he offered some to a guest, who took a big spoonful.
The guest let out a huge gasp. When he was finally able to speak, he choked out, "I've heard many ministers preach hellfire, but you are the first one I've met who passes out a sample of it."