Partirse el pecho de risa

[ROBINDESBOIS]

when sth is really funny and we start laughing and can´t stop, we say partirse el pecho?
ENGLISH?

[pjt33]

To split your sides laughing.

[Rusty]

Also:
To bust a gut (http://www.tomisimo.org/idioms/en/to-bust-a-gut-4659.html).

[pjt33]

Also:
To bust a gut (http://www.tomisimo.org/idioms/en/to-bust-a-gut-4659.html).
Oh. I thought that was to make a big effort, conceptually related to overdoing it and getting a hernia.

[poli]

I have heard split a gut for something truly hilarious.

[Rusty]

Oh. I thought that was to make a big effort, conceptually related to overdoing it and getting a hernia.You're correct. The phrase has both meanings.
I've heard Poli's contribution before, and a couple of others.
'To laugh one's head off' (and other body parts) is another very common way to say the same thing.