wet one's pants

The senses referring to laughing and being afraid are extensions from the literal (urination) sense; both involve an element of variably literal or figurative nature: they are generally figurative, but if one laughs hard enough or gets frightened badly enough, the wetting may sometimes happen literally.

• "If you keep on refusing to excuse anyone for a bathroom break, you're going to force someone to wet their pants. Don't go overboard with it."
• "Pretty much the whole night at the comedy club was hilarious, but that encore by Taylor Tomlinson had me wetting my pants."
• "He just about wet his pants when he found out how many accounts receivable were still outstanding."

• scaredy pants