There's a popular bar in my neighborhood that is perfectly passable except for the fact that it serves beer in plastic cups. Not the flimsy red cups native to every college party, but the sort you'd expect to find at a local Salvation Army or a barbecue joint; opaque and pebbled, in mismatched colors. Sort of like this.
Is it whimsical and fun? Maybe to some (this bar is in Brooklyn, after all). But to even a casual beer enthusiast, the practice should be verboten.
The characteristics of various beer styles are best displayed, and enjoyed, in a range of beer glasses, each tailored to showcase particular facets of a given brew. And it's not just snobbery; it's science. The appearance of a beer can impact your perception of its taste, while the design of a glass can influence what part of the tongue does most of the tasting.
So what beer glass should you be using? To the cupboard!
Weizen glass

Best for: Hefeweizen, Dunkelweizen, anything with "weizen" in the name, American wheat ales
Tulip glass

Best for: Saison, Belgian strong ale, barleywine
Pilsner glass

Best for: Czech and German pilsners, blonde ales, American adjunct lagers (Bud, High Life, etc.)
Pint Glass

Best for: stouts, porters, pale ales
Suitable for: most anything, in a pinch
Goblet/Chalice

Best for: Belgian abbey beers (Dubbel, Tripel, Quadrupel)
Bonus: Stein/Mug/Boot

Best for: liters of German lager, but realistically, since these glasses are all about sheer volume and toasting, any beer at all.
There are plenty of other styles and sub-styles of glassware out there. Some breweries have even devised their own proprietary glassware for everything from stouts to IPAs; Sam Adams has a laser-etched "Perfect Pint Glass."
If you're a beer fan, please use the proper glassware. And if you aren't a beer fan, enjoy your corn water. I know a bar that will even pour it for you in a plastic cup.