I'm going to spike the water cooler
Why would you spike the water cooler?
Because it's funny to see people get sick after drinking the water.
This is a very dangerous prank. Spiking people's drinks is a felony, and you could be unintentionally poisoning your co-workers on top of losing all of their trust. Find a more suitable prank to do.
Psh. People need to learn how to take a joke.
There's nothing funny about drugging people by spiking their drink. That's a serious crime that could result in killing someone. You really should be more considerate toward other people.