Seriously because Prost is NOT an acronym where the answer are actuually easily searchable, and not only that there are TWO stickeys at the top of the forum call "acronyms" and "Often used slang" or something like that, and where there are ton of OTHER threads asking what Swambo is. Like once a month. So that's why we like to play with anyone who doesn't bother to look, at the answers CLEARLY around them (good naturedly of course.)
Prost is NOT easily found on here, and in fact I can only recall one other thread, maybe 2-3 years back, when TX installed the prost button. So really searching would not have easily found the answer....therefore we took pity on the poor soul and decided to help him.
Or we just like the ole "I'm gonna build a mashtun hot tub" codger better, because he is slightly nuts, and god favors those types of folks, according to the old Irish tales.
Same as "Kampai!" in Japanese. Which, literally is "Empty the cup," so the most literal equivalent in English would be "bottoms up." However, there are so many things, and in all languages, that are not literal. It's all "Cheers!"