crack up over sth

crack up (over sth) (to find something very amusing, to have laughed very much about something) — хохотать, смеяться до упаду; покатываться со смеху; умирать от смеха

Example 1: His story was so funny. We were just cracking up!

Example 2: I was cracking up when Jenny told me how she had to walk through the mall without shoes.

crack sb up смешить, рассмешить

Example: Are there any comedians that crack you up?

see also
[лопнуть от смеха]
[split one's sides]
split a gut
laugh one's head off
животики /живот(ы) надорвать
[bust a gut]
[have sb in stitches]

[get a kick out of sth]