every one of them on the fly and as far as i know, original
because they're one liners i can't 100% guarantee that a similar joke hasn't been arrived to before independently, or that once in a blue moon i think i'm coming up with something original but i'm subconsciously taking a joke i've heard before
but pedantry aside, it's all my own stuff, and i don't even take the thousands of lines i've done before on twitter, always new
that being said it's not easy, sometimes i can't come up with a good line even after half an hour of hard thinking. It's just a lot harder coming up with a line from a blank canvas than a witty retort in a conversation. People think just because these lines are short, they're easy. Maybe i'm very stupid but at least in my case it's not true