Next time, if you don’t feel like shaking your head a lot, try this trick..
Tilt your head to the side so that the ear with the water in it is facing up toward the sky (head parallel to the ground).
The following has to be done in quick succession: run the tap or dip your fingers in a cup of water, essentially get some water on your fingertips and quickly bring it to your ear, letting drip a drop or two of water into your ear. As soon as the water rolls in, quickly tilt your head over, so that the ear that was up is now down.
The idea is that water has tensile strength amongst its other properties, so the water you purposely drip in will attach to the water in your ear. With the right momentum and timing, the dripped-in water will grab the trapped water and you can get it all to roll out at once.