Everyone knows drunk people are terrible at judging how wasted the are but now Australian researchers have the data to prove it.
Deakin University drug and alcohol researcher Dr Nic Droste hit up pubs and bars around the country armed with a breath tester and a question - on a scale of zero to 10, how drunk are you?
He and his fellow researchers found when people reached about twice the legal blood alcohol limit they could longer tell how drunk they were.
"Drunk people are quite literally not capable of making responsible decisions," Dr Droste told AAP.
While this does not come as any surprise, the researchers from Deakin, La Trobe and Curtin universities found they were quite accurate when it came to rating how drunk people were.
"In a busy environment it can be difficult to isolate those who are just a bit tipsy and having a good time from those who are just far too drunk," Dr Droste said.
"We were really surprised that one one had measured intoxication levels in nightlife districts before."
They spoke to more than 7000 people across Sydney, Melbourne, Perth, Wollongong and Geelong, some designated drivers and others so drunk "we stopped the interview and made sure they were OK".
"A lot of people were just interested to talk to someone," Dr Droste said.
"It doesn't sound very romantic, to talk to an interviewer, but some lonely people out there just wanted to chat."
The takeaway from all this is emphasising the importance of responsible alcohol service.
People are generally too drunk to keep drinking when stagger or fall over, slur their words or become incredibly boisterous or confused, Dr Droste said.
"(Venues) have got a responsibility to their patron," he said.