I learned DOS by waiting for my dad at his job. Searching through the work-computer for games. "what files can i try?" "anything that ends with .com or .exe". I literally tried every com/exe file. My search bore fruits though, I found that cat game which i don't remember the name of, the one where you catch the babies from burning houses, and "Adventure", which I didn't like, mostly from the fact that I didn't speak english. I have no idea how old i was, but probably 7-10.
Some years later I learned english with Sierra-games, the first one being Leisure Suit Larry. In retrospect, I guess that explains a thing or two.. (I'm 29 now). Also it boggles me how my parents could give me some of the words i asked about with a straight face. But I remember they didn't know what a prophylactic was, so I had to figure out that one by myself. Which was no small task. No google or bigtittedmamasitas.com those days.