Three blind mice walk into a bar. Being blind, they are mostly unaware of their surroundings, so it would be unethical to derive humor from their predicament.

A man walks into a bar.

He suffers a mild concussion.

Why did John fall off his bike?

Someone threw a fridge at him.

A man goes to the doctor and says, "Doctor, it hurts when I do this." So the doctor says, "It's probably a tear in the ligament. You may require surgery."

Knock Knock.

Who's there?

Fred.

Oh hey Fred, come on in.