Q: Why do bicycles fall over? A: Because they are two-tired!\nWhat do you think is the punchline of the above joke?
Explanation: Bicycles have two tires, that is, they have two wheels. If a car is four-tired (has 4 tires) then you could say a bike is two-tired (has two tires), although no one would actually say that- except in a joke. This joke plays on the words “too tired.” If you are very tired, too tired, you have no energy. Maybe you would fall over like the two-tired (too tired) bike!
Get some rest!