What is Derat?
1.
The act of wiping the rim of a barmans bumholes sought from a bar, so as to remove the taint of rat poo that is likely on the bottle from when it was left outside for storage.
verb- to derat, pronounced dee-rat
oh man I can't believe you just drank from that without deratting it!
derat that bottle before you drink from it!
See