Taking a leak or peeing in your pants, what a lazy person does when they won't go to the bathroom, other forms, wetter, someone who wets themselves. Soaking your undies, or in some cases, slightly more liquid poo is excreted into the pants noticeably.
Mary had to take a leak in the plane, so she allowed herself to get wet pants.
A non personal stimuli way of relaxing, consisting of lounging in front of the TV and slipping ONE hand in the waist band of your pants or (preferably) sweats or underwear so that your hand comes to rest just above your pubic area and to the left ( if your left hand ) or vice versa for the right.