Блин- bleen - a pancake or 'crap' as in an exclamation
When I first lived in Russia I taught English at a school where wrestlers were training. After my classes I would hang out with these wrestlers and just shoot the breeze and try and learn Russian. Well one word that I heard these wrestlers saying all the time was (one of many) Russian f-words and it begins with БЛ... Well, I heard them saying it CONSTANTLY, felt like it was obviously a very important part of Russian speech and so I asked what it meant. One of the wrestlers tried to explain (they didn't speak English at all) by picking up a book and dropping it on the floor and then casually saying "БЛ***". So I thought to myself, "Oh, it's like what you say when you drop something or something not good happens. Easy enough". So I went around saying that when even the tiniest misfortune befell me.
It wasn't until many months later when I was back home in America with a new set of sportsman that I was acting as a chauffeur and host for, that I took a wrong turn and casually said, "БЛ***". These boys exclaimed/giggled. They explained, "не надо сказать такое слово, лучше сказать БЛИН" (Don't say that word, it's better to say 'crap'). So just like 'fudge' is a euphemism for "f***" simply because the first part of it sounds the same as the bad word, Блин is a euphemism for a much more offensive, similar-sounding word. So that's how I came to learn the word блин as a much more appropriate word to say when you drop something, take a wrong turn, or when something not good happens.