We nearly split our sides laughing watching Paul trying to give the rabbit a bath.
idiomsplit your sidesold-fashioned to laugh a lot, and very loudly:The two comics keep up a stream of backchat that will have the audience splitting their sides with laughter.side-splitting: Reg kept us amused with a side-splitting imitation of Prince Charles.
Note This idiom is often used sarcastically when you do not think something is funny at all (see note about sarcasm at why break the habit of a lifetime?)"They liked that joke when I told it down the pub." "I'm sure they were splitting their sides."
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 your sides
be convulsed with laughter. informal
split your ˈsides (laughing/with laughter)
laugh a lot; laugh loudly: When she started singing in that funny voice, we nearly split our sides.