i can do this to, but i think it might be unsafe.
as you prob know, the lubricant in your fingers seperates into gas and liquid. when you crack your knuckles, the gas "pops" back into the liquid making a mix, and over time they seperate. this isnt dangerous. but you shouldnt be able to do it much more than every 15 min max. if you can do it whenever however many times you want, i think it might be cartilage or bone snapping past eachother, which could wear down the cartilage and lead to arthritis. so i dont do it that often