I will add that although "to crack (someone) up" means to to make someone laugh, a similar idiom, "crack up" can have two very different meanings, depending on the context: (1) to break out in laughter. "The comedian was so funny that the entire audience cracked up." (2) to have a mental breakdown. "After John's wife died, his house burned down, and he lost his job, he completely cracked up."

What does "crack me up" mean? What is the meaning of "crack me up"? (Notice the sentence structures.) It usually means "make me laugh (a lot!)".

It usually means it made you laugh, e.g. He cracks me up = He makes me laugh