I've never been onto a bar, but on TV and in films, there is often a scene when the main character is a little sullen, or stressed, and he goes into a bar, and asks for "a strong one". I think this means something with a high alcohol content, but what type of alcohol are they referring to? Whiskey? Gin, Beer? Vodka?
Well, they don't mean anything in particular really, because this is fiction. However, if we want to play analysis, the answer would certainly be whiskey, American bourbon most likely. Let's go through the choices.
1) Wine. No way. If someone is going to generically order wine, they at least specify a color, red or white. Plus wine is mostly all the same strength, only varying a couple percent either direction, unless you count fortified wines, which are another topic.
2) Beer. Ordering a generic beer would get you a basic beer, which isn't very strong. Only a few specialized beer bars would have any beers that I'd call really strong. Any beer stronger than 12% is going to be very rare, with most bars not even having above 8%. The kinds of people who order strong beers, these 8, 9, 10, etc beers, would always order by name. They are craft beer fans. These aren't really strong enough to help someone in distress.
3) Vodka. Unless you are a Russian or a huge vodka fan, you don't order vodka straight like this. Vodka is generally for mixing in America. The people who are serious about vodka drinking would order by brand name.
4) Gin is the same story as vodka really. Gin in generally served in mixed form, although a dry gin martini is close to 100% gin, it still counts as mixed.
5) Cordials, liquers, etc. Again, would be ordered by type or brand, and often not that strong compared to the main liquors.
6) Rum, can be quite strong, makes decent shots, makes decent sipping. But it conjours up images of pirate and or topical locations. If the movie is set in the Caribbean, they would mean rum.
7) Tequila. It's strong, makes good shots. Not so great for sipping, unless you are talking about the really good stuff or you are a tequila fan. If you are in Mexico or a Cantina, they would mean tequila.
8) Whiskey. This is the winning category. It's always strong. It tastes good in shots, and makes fine sipping from a glass. This is manly and good for all classes of life. Blue collars and white collars alike love whiskey. if you are doing, "forget your troubles" kinda drinking, whiskey is the best choice. If you are sad, or upset, or worried, or looking for a fight, or anything like that, whiskey is the best choice. A real American manly man is going to want whiskey, usually bourbon, something like Knob's Creek. Some will prefer Irish whiskeys, or Scottish Whiskys, (notice no e), but if they do, they will say so by name.
I mean, I know if I was upset like that and going to a bar and said a stupid order like gimme a strong one, I would mean bourbon. If I wanted a beer, to get back on topic, I'd be like, "What kind of IPAs you got?" "Any sours?"