A scale used to rate girls/boys, measured in drinks, or in other words how many drinks till you would fuck them.
Obviously the more drinks the more drunk you are/ the bigger a munter he/she is. The words 'sober' and 'reavered
' can also be used to express your feelings towards someone incredibly hot and the biggest, fatest, smelly bitch goin'.
Simon: Wow, she's not bad. How many deep?
Simon: What? Are you serious?
Kevin: Get the fuck away from me you dickslap