The word "leint" is an
English verb dating backing to the mid-17
th century. It's derived from another old
English word, "
lant", meaning "
urine" and, as far as I can tell, was only used in association with the practise of adding
urine to
beer to strengthen it, (
"to leint ale").
This explains the follow drink-related idioms:
"(going out) on the piss" : A night on the town with the express aim of getting drunk
"pissed" or "pissed up" : state of being drunk
"a piss-up" : A drinking session
"a piss-up in a brewery" : An easy-to-organise drinking session