Hi J. - Maybe I'm missing something here, but based upon your examples, I don't see where what she has said is SO strange. She's six. Sounds typical to me. At that age they're exploring their thoughts, trying out new associations...and seeing what kind of reactions these new ideas elicit.
I could imagine the tape felt funny on her foot (taped feet are not the norm) and although she chose not to say anything out loud until the next day, it probably was on her mind a lot -- hard to avoid. So while you say "for no reason," there actually seems to be an obvious reason. So she called it duct tape. And why is "see you in a 1000 months" so odd for a little kid?
Maybe she's more imaginative than her friends. Or maybe this is her sense of humor and you're just missing the jokes? Either way, I'd say lighten up. She's not blurting profanities or improper comments. She's not being mean to anyone. And although they look at her strangely sometimes, her friends are still her friends. This is a great time to watch your child's own unique personality truly begin to unfold.