Should I teach the "farmer spray" way to blow the nose? When?

I confess, I farmer spray all the time while running and biking.  For those that may not know what I'm talking about, I plug one nostril and then blow my nose as hard as I can so I spray snot without it hitting me on the arm, shoulder, back, or on the bike.  Repeat with other nostril.

I don't know when or how I learned this but I am really grateful because it's the perfect answer during exercise for nasal drip (or flow in my case).  As a courtesy, I check behind me and beside me to make sure I don't spray on any people, precious property or pets.

I forget how repulsive this may be for people driving by or in my case, sitting in the restaurant and coffee shops.  I try to wait for the politest descrete place but wonder if seeing a runner with snot running down his face may also spoil the appetitie.

I took a poll in my office and all the female runners thought I was disgusting for spraying rather than using a tissue.  My wife is a runner and she accepts the farmer spray as a perfectly acceptable way to deal with a runny nose.

Now the big question, I think my daughters should learn how to do this.  However, I don't know when or how to teach them.  I'm afraid that at 2 and 3 years old, they would start doing it in our house because it is so convenient.  I also don't want to be the only parent at the play ground who's kids are doing this.  I want them to have the judgment to do this socially unacceptable behavior only at certain times.

Finally, is there a way to teach this that doesn't cover their clothes in snot?  Should I work from standing spray to walking, and eventually to a run.  What skills should they have on the trike before learning?

I need help with this important matter.  Thanks in advance.