Re: back in those days...
When I taught scuba diving (I still do actually) I often used to make my trainees laugh rather than tell them to take their masks of underwater and refit them. When you laugh underwater, your eyes wrinkle, your cheeks bulge out and your mask floods with water. That way, you have to deal with it.
The boring way is to get your trainee relaxed, kneel them down on a sandy bottom, then instruct them (leading by example) to remove their mask by pulling it away from their face, placing it back against their face, top against their forehead, holding the bottom out, and expelling air through their nose. Boring boring boring.
I found a much more fun way was to tuck pieces of seaweed under my hood so it stuck out like hair, while swimming underwater behind them. I would then approach them, tap them on the shoulder, look them directly in the eyes and give them a serious but inquisitive "Are you OK?" signal, with a very concerned look on my face.
They would first be completely wide eyed, not recognizing me as their instructor, or wondering what on earth was going on. Pretty quickly they would work it out and burst out laughing underwater for the first time in their lives, their mask would flood, and they would deal with it instinctively. Much more fun than wasting time doing boring training routines.
Seaweed hairstyles weren't my only method. I don't give away all my secrets ;)