<unk>  is the formation of gas bubbles in bodily fluids due to reduced environmental pressure, for example at high altitude. It occurs because a system of liquid and gas at equilibrium will see a net conversion of liquid to gas as pressure lowers, for example, liquids reach their boiling point at lower temperatures when the pressure on them is lowered.
Ebullism
Enamel pearl
Black hairy tongue
Omphalolith
Hamartia 
Aphalangia
Amastia
Caviar tongue