Knock Knock: Drink of Less

[yetadem]

A guy walks into a bar and approaches the barman, "Can I have a drink of less, please?" "I'm sorry sir," the barman replies, looking slightly puzzled,

"I've not come across that one before. Is it a beer?"

"I've no idea," replies the guy, "The thing is, I went to see my doctor last week and he told me that I should drink less."