Possibly the biggest barrier to overcome (loss of equilibrium is a close second) is a complete loss of speech control. Not only will a drunk friend lose control of what he/she says, but to whom he/she says it to. This unique vibration will alter the air particles in the general vicinity and cause some objects to effectively become lighter, or even weightless. Be warned that various objects (drinks, hands, even barstools) are susceptible to this effect.