If we are addressing a bag of weed, specifically, it could be handled in various ways using [an approach to communication] called NLP—Neuro-Linguistic Programing—meaning a skilled magician can apply the best strategy to either charm, entertain, influence, or manipulate the situation.
Every case is different, but let’s say I was caught with some weed. Besides that obvious approach of vanishing it with sleight of hand and fast thinking, I might say the opposite of what a cop would expect like "YES! This is weed! My friend James let me borrow it so I could film this funny YouTube skit. James has a card and legally uses weed… I do not use it!"
Having a YouTube video script always in the pocket to confirm the “story” could be beneficial as a way to plan ahead. However, you’d be using that as a contingency in the event you did not come up with a strategy on the fly using observation, magic skill and/or influence.