Crack up and Go off deep end

Crack up verb - To declare enthusiastic approval of.

Go off deep end and crack up are semantically related in break down mentally topic. In some cases you can use "Go off deep end" instead a verb "Crack up".

Crack up and go off deep end are semantically related in lose control topic. Sometimes you can use "Crack up" instead a verb phrase "Go off deep end", if it concerns topics such as become insane.