So I was doing something completely unrelated to anything involving Japanese when I ran into one of the words I listed here. I was playing a non-Japanese game (Infamous 2)*, when a new trophy popped up that said: しっぺ返し. Sweet, I just learned that word! What are the odds that a word I just learned popped up so soon in some other completely different place? They must be pretty good, because it happens all the time!
*So if you set your language settings for your PS3 to Japanese, the trophies are translated into Japanese for some games even if the game itself doesn’t have a lick of Japanese in it.