Foggy Glasses

Back when I used to teach diving, we could usually get people past the gross out of spitting in their masks by telling them that the bottled spit came from people sitting around in (name your favorite country) and spitting in the bottles.

Once they were over it, we'd really gross them out by one of us turning to the other and saying, "My mouth is dry, spit in my mask for me?"

It also works well in our swim goggles.

I think a mild soap solution works too, but look it up. Spit is way more fun!