You may laugh, but this one is important.
If ever, when you are washing your hair, you get a dollop of shampoo in your ear - don't foolishly try to rinse it out with water.
The result? A ridiculous amount of bubbles, soap in your eyes and temporary ( I hope) deafness.
I can't think of an alternative to water. But you could just avoid getting it in your ears.
Take it from someone with first hand experience.
If you perhaps feel like booking a place on an online seminar [webinar] broadcasted from the USA, make sure you are fully competant in your understanding of US timezones in relation to GMT. Otherwise you end up biooking the wrong session and then waiting an hour with wet hair, bad hearing and an overwhelming desire to sleep. But of course, this isn't me.