Quote Originally Posted by sefbarisovich
that reminds me of a question I had. I've heard russians use 'poshli' as 'lets go'. Doesn't that mean 'we left'?
Not quite. Strictly speaking, this is past plural form, and it's original meaning is "we/you/they left". In your example, it is used as an imperative.

Quote Originally Posted by sefbarisovich
I'm assuming its like the english slang phrase 'I'm already there'-

like 'Dude, lets go get some beer and go pick up chicks'
'I'm already there!'(I'm way ahead of you)[slang]/(lets do it!)[normal]
Not at all. "Пошли" is neither slang nor facetious or figurative. It simply means "Let's go (right now)". It is THE way to say this in Russian.