crack up

British  

verb

1. (intr) to break into pieces

2. informal (intr) to undergo a physical or mental breakdown

3. informal (tr) to present or report, esp in glowing terms

   it's not all it's cracked up to be

4. informal to laugh or cause to laugh uproariously or uncontrollably

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noun

1. informal a physical or mental breakdown

crack up Idioms  

1. Suffer an emotional breakdown, become insane, as in He might crack up under the strain . This usage alludes to the result of cracking one's skull; from the early 1600s to crack alone was used in this way. [ Slang ; early 1900s]

2. Damage or wreck a vehicle or vessel. For example, I'm always afraid that I'll crack up the car .

3. Experience a crash, as in We cracked up on the freeway in the middle of the ice storm .

4. Also, crack someone up . Burst or cause to burst out laughing, as in The audience cracked up , or That joke really cracked me up . [ Slang ; c. 1940] Also see break up , def. 6. All of these expressions derive from crack in the sense of “break into pieces” or “collapse,” a usage dating from the late 1600s. Also see cracked up .

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Example Sentences

See Examples For:

crack up

Padilla and Gosling were a teacher and principal in another sketch reading passed notes out loud that, according to text on screen, were swapped out since rehearsal, causing both to crack up uncontrollably.

From Los Angeles Times ● Mar. 8, 2026

It's not clear what made him crack up, but we bet Paul Giamatti had something to do with it.

From BBC ● Feb. 13, 2024

If the phrase “mom jeans” makes you instantly crack up, you will love this show.

From New York Times ● Feb. 8, 2024

Developers first drill a well and inject high-pressured water to crack up underground rock.

From Scientific American ● Feb. 14, 2023

“He doesn’t have any friends,” Annabelle says, and she and Olivia crack up.

From "A Heart in a Body in the World" by Deb Caletti

Related Words

• freak out
• go crazy