These aren't very important questions; they're just ones I wonder about...
In anime they frequently use いくぞ to mean "Let's go". To me it appears to be the dictionary form, いく, with ぞ stuck on the end. Is that correct? And if so, how does it work?
In anime they also frequently use しまった, meaning something like "dammit". It appears to be the plain past tense of しまう (仕舞う) which means to finish or complete something. Is that really where it comes from? And if so, how does finishing something become a kind of curse (or is it one of those things that nobody knows, it's just the way it is)?
マイケル