Definition of crack up phrasal verb from the Oxford Advanced American Dictionary

 

crack up

 phrasal verb
phrasal verb
 
jump to other results
Phrasal Verbs

    crack up

    (informal)
     
    jump to other results
  1. 1 to become ill, either physically or mentally, because of pressure You'll crack up if you keep on working like this.
  2. 2to start laughing a lot He walked in and everyone just cracked up.

crack somebody up

(informal)
 
jump to other results
to make someone laugh a lot Jill's so funny, she just cracks me up.
See the Oxford Advanced Learner's Dictionary entry: crack up