Why do some people put olives in their beer?
Apart from the obvious reason, because they can, they seems to be couple of reasons for this.
Some individuals actually enjoy doing it.
Olives are paired quite nicely with some varieties of beer.
For some it is a sort of tradition: beertini.
It is part of barroom culture in the Midwest.
Olives still have that ...
Yum! Because it's delicious! Despite using a New Glarus glass, my favorite beer to add sinkers, (Olives) to is Hoegaarden. Otherwise a cold & cheap Miller Lite does the trick. Olives add a briney, salty kick of flavor. Especially good in hot weather. I'm from Southern Minnesota and we call olives sinkers.
Some folks prefer a pickle to olives. Usually ...
I'm from the Midwest, and this is very common. I've done this for years, and since I became gluten free about 8 years ago (not by choice), I do this often. The gluten free beers are not that great, so adding olives or making it a red beer helps with the taste.
Vanilla ice cream in Jagermeister
Orange sherbet in Bailey's Irish Cream (it's like an adult dreamsicle).
As @Rory mentions, ice cream cocktails automatically become sweet and creamy, which is why I find sticking with liquors that you expect to be sweet and creamy pair very well.
Per your original mention of the classic root beer float, I ...
One of the great ones we grew up with was the Cider Spider - a cider float with vanilla ice cream, using proper cider, not the strange thing that seems to pass for cider in the US. I assume it came from Australia, as it was my mother who introduced us to it.
But since then experimentation has showed that most basic ice cream flavours can work well in fairly ...
This is a very interesting post, as I would never do such a thing as I prefer Bourbon Barrel Aged Beers, so olives in that would be odd. There is a beer called Salty Lady with is a Gose that tastes like one mixed pickle juice and peppercini juice for that really sour flavor...