I'm a healthy 23 year old male. Not sure what it is but I have been doing it for a couple of months. Every now and then just out of the random, my lungs will involuntarily suck in a small burst of air. It doesn't hurt or anything, just kind of curious if anyone else has done it or knows what it is. I have had allergies for quite some time and I have a very mild form of asthma. It hasn't caused me any problems that I know of, just something that I notice every now and then. It's hard to explain but it's almost like a pure oxygen bubble being dropped into my lungs.