"Urge incontinence" is when you feel sudden, intense urges to go, seemingly out of the blue. One type is informally known as "latch-key incontinence" -- it's when you feel a sudden urge to go, often when you're getting close to a bathroom but there are still things in the way (you have to unlock the front door, or take off your coat and boots, or finish walking up the street, or you're stuck in a traffic jam, etc). With practice, you can learn to resist it, but it's still annoying. Other types include waking up in the middle of the night and knowing you have to go NOW!

A lot of it is related to an involuntary muscle called the "detrusor muscle," which squeezes your bladder. You can't control it consciously. If it gets it's signals crossed, and can start squeezing at the wrong time, and then you have to fight it with your other muscles (almost like arm-wrestling yourself). There is a prescription medication called "Myrbetriq" that can relax the muscle in the case of an over-active bladder (e.g. waking up every couple of hours at night).