Thanks. I’ve been able to do this intermittently all my life, but rarely practise it as I’m over the age of 40.
I’ve now just doused my laptop.
Crap, I can’t do it on command, but I’ve managed to accidentally spit on my keyboard. Thanks a lot SDMB! 
How much do you want?
I sometimes do it while yawning. I don’t remember ever seeing anyone of any age do it on purpose.
Are you serious? I’ll teach you. PM me. 
I can gleek at will, but I have to take out my bottom teeth to do it. On the other hand, it does accidentaly happen at random, usually when I’m talking to someone up close. Very embarassing!
I can gleek too - I can get it to go a long way, like ten feet or so. Sometimes it happens by accident when I yawn.
I like to think of myself as akin to a cobra, but actually I look like a dork.
One time on the school bus I gleeked over the bus driver’s head all over the windscreen. The poor bastard thought he was going mad!
You would have won Freak Night at my summer camp. The guy who could blow air out of his eye always won, but this would have beat him.
Thanks, all! I’m glad I’m not a complete freak of nature. Just partially…
Joe
Another great user name/post combination
Watch out Annie, or you’re next!!
When I had a version of the mumps a couple months ago, I could open my mouth, lift my tongue, the press on the salvia gland under my chin to make saliva shoot out. My boys thought it was the coolest thing ever. Since the cure, I’m no longer cool.
Just eat something sour (even just thinking of something sour can work. Pavlov, anybody?), and then push the underside tip of your tongue against the roof of your mouth. Depending on how your mouth is shaped, you may have to push more forward or more towards the rear of your mouth.
I accept PayPal.
Salvia gland? I’ll bet you have teenage goth kids following you around everywhere 
My sister has the unusual ability to flare her nostrils and move the dimple on her chin in and out. At the same time. Dimple in, nostrils out. Nostrils in, dimple out.