split (one's) sides
To laugh uproariously or hysterically. Your jokes are perfect for your speech tonight. You'll have them splitting their sides!
split one's sides (with laughter)
Fig. to laugh so hard that one's sides almost split. (Always an exaggeration.) The members of the audience almost split their sides with laughter. When I heard what happened to Patricia, I almost split my sides.
split one's sides
Also, laugh one's head off. Be extremely amused, laugh uproariously. For example, That comedian had us splitting our sides, or Jane laughed her head off when she saw Rob's costume. The first of these hyperbolic terms dates from about 1700.
split your sides
be convulsed with laughter. informalsplit your ˈsides (laughing/with laughter)
laugh a lot; laugh loudly: When she started singing in that funny voice, we nearly split our sides. split one's sides
To laugh heartily.