i was a bar tender for about 2 years and then ran a bar for a year.
in australia the rules are a little fuzzy when it comes to shots
one shot is meant to be a standerd drink which contains 10mg of alcahol however when drinking spirits such as jager or vermoth where the alcahol content is alot stronger then say shnapps bar tenders usually pour the same amount which is 30 mils into a shot glass, you will also notice that at a bar when ordering say a rum and coke the bar tender for legal reasons should not free pour but put 1 shot in a glass then fill with coke.
and as for the drinking 25 shots in a night well i couldnt do it and as a bar tender i would have around 5 or six shots at work over a night then start drinking in the morning with the rest of the staff and have andother say 10 so around 15 shots (this also includes things like rum and coke) and i would be tanked. i would do this 4 or 5 times a week so i am a pretty regular drinker.
i have also seen people at bars drink around 30 shots and be able to walk out of the bar, and once i have seen a guy do 40shots in a night plus beer however he wasnt walking by the end of it.
so the morale of the story is year you can do it but you need to have alot of body fat, a strong liver (drink alot and dont smoke) and be drinking fairly regularly