While we're on the subject of neat little tricks.
1- Cough up a good mucousy blob of flem, the more sound effects the better, and rub it around the inside of your mask and (when boat diving), leave it there until you jump in. Then rinse your mask once you're in the water. Waiting until after you're in the water almost eliminates the possibility of losing it over the side and most divers won't appreciate it if you rinse your muscous filled mask in the rinse bucket. If you have the proper blend of sputum it will work better than anything on the market and you've always got a supply "on hand". Once you've got the attention of everyone on board and a mask full of goopy phlegm, be a good diver and offer some to everyone else on the boat. You will find that some divers are reluctant to take advantage of your offer so take the initiative and spit in their masks anyway. They'll show you how appreciative they are.