For a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional. Or Boyle's law is a gas law, stating that the pressure and volume of a gas have an inverse relationship, when temperature is held constant. If volume increases, then pressure decreases and vice versa, when temperature is held constant.
Yeah, except when it's not. The two fingers held aloft in a V are fine provided your palm is facing out, but in some countries -- namely, Australia, New Zealand, and the United Kingdom -- it's an insult of the first order if you make the same gesture but with your palm facing inward.
It could also mean a gesture to get someone to call you, the hand sign acts as a imaginary phone. What it means to others: In Spain, Equador, Chile, Russia and Germany this sign could be used to suggest having a drink, the hand sign acts as an imaginary bottle or glass.