I was watching this stand-up show on tv, and this guy said "Two months ago I'm walking down the street and this is walking toward me...". And that's how the conversation started, he didn't say anything like "Two months ago I was walking down..." and at some point go off track and then doubled back to the main thing, saying "So, two months ago i'm walking down the street...". The joke started that way.
I'm just curious whether it's okay to talk like that. Is it grammatically correct?