split one's sides, to

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.
See also: side, split

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.
See also: side, split

split one's sides

To laugh heartily.
See also: side, split

split one's sides, to

To laugh uproariously. This hyperbole dates from the seventeenth century. Thomas Brown used it in Saints in Uproar (1687): “You’d break a man’s sides with laughing.” The word “split” came into use somewhat later. Dickens used it in The Old Curiosity Shop (1840), “He bade fair to split his sides with laughing,” and Harriet Beecher Stowe in Uncle Tom’s Cabin (1852), “I laughed fit to split.” See also shake with laughter.
See also: split