Two men walk into a bar. One man orders H2O. The other says, “I’ll have H2O, too.”

The second man dies.

Explanation: This joke uses chemistry for its humor. The first man orders “H2O,” which is water, but the second man unintentionally orders “H2O2,” which is hydrogen peroxide, a harmful chemical. The punchline comes from the misunderstanding of “H2O, too,” resulting in the second man’s death due to drinking a toxic substance, creating a darkly humorous twist.