scare the pants off

ants in one's pants

The condition of being agitated and constantly fidgeting.

beat the pants off

To thoroughly and decisively defeat someone, either in a physical fight or, figuratively, in a competition.

caught with one's pants down

Caught off guard, unprepared, or in an embarrassing situation.

fly by the seat of one's pants

To pilot an aircraft without the aid of instruments and without a flight plan, using only instinct, visual observation, and practical judgment.

get into someone's pants

To have sex with someone, especially for the first time.

keep one's pants on

To stay calm.

lick the pants off

To thoroughly and decisively defeat someone, either in a physical fight or, figuratively, in a competition.

pee in one's pants

To laugh uncontrollably.