Let’s talk about the logistics of the stag night, shall we?
According to the directions that Sherlock gave the bartender at the beginning of the night, each beer that he and John drank was 443.7 ml. Converted to fluid ounces for the American over here that comes out to roughly 15, or an ounce shy of a standard American pint and five ounces shy of an imperial pint. Which means they weren’t even drinking full beers.
Counting how many drinks they showed us on screen and remembering that Sherlock said they would only have one drink at each location as you would for a standard pub crawl, they had
- Four regular beers out of their beakers
- 1 shot of an unknown liquor (looked clear, possibly vodka or tequila)
- Another beer to chase the shot
According to Mrs. Hudson they were out for two hours.
So to sum up, they each had five (more like 4.5) small beers and one shot over the course of two hours and got blackout drunk enough to fall asleep essentially cuddling together on the stairs. One more drink who knows how long later got them arrested.
Lestrade was right, they are fucking lightweights.