crack%20up

To laugh heartily.

“It was hilarious. We were cracking up the whole time.”

To cause to laugh heartily.

“The joke about the nuns in the bath cracked me up.”

To become insane; to suffer a mental breakdown.

“She got through the war, but cracked up when her sister died.”

(usually passive, usually negative) To cry up; to extol.

“This new computer system is not what it was cracked up to be.”

(of an aircraft or automobile) To crash.

Funny; hilarious

“That joke was crack up.”