CRACK UP

{v.} 1. To wreck or be wrecked; smash up. * /The airplane cracked up in landing./ * /He cracked up his car./ 2. {informal} To become mentally ill under physical or mental overwork or worry. * /He had kept too busy for years, and when failures came, he cracked up./ * /It seemed to be family problems that made him crack up./ 3. Burst into laughter or cause to burst into laughter. * /That comedian cracks me up./