One time I was showing someone a trick and I was revealing her card to her and I said, "It's a picture card." And she wrinkled her face at me. So I said, "Is it a picture card?" And she said, "They all have pictures on them." And she's right. All cards have pictures on them.
I no longer say picture cards, spot cards, court cards. If I have to differentiate them I talk about cards with numbers and cards with letters. This may make me sound stupid to someone who knows cards. That's fine. I just don't want to trip up people who don't play cards or handle them regularly. And nobody has any trouble understanding the difference between numbers and letters.
When giving directions, my goal is to constantly streamline things. If two spectators misunderstand the same thing in a trick I perform on two separate occasions, I will rewrite it. I don't care. I'm not precious about the words I use, only about being understood.
I think everyone agrees that saying "riffle" is dumb. "As I riffle through the cards..." No. "As I flip through the cards..." Yes. But I think the reason people are willing to give up on riffle is because it's a stupid sounding word. So is dribble. Unless you're doing a trick with basketballs or where you fix someone's faulty prostate, I wouldn't use the word dribble.
It's easy to forget that people aren't familiar with the names of shuffles, even if they do them. "Can you give these a riffle shuffle?" "Can you give them an overhand shuffle?" Whenever I hear someone say that in a performance I know that they either only perform for other magicians or never perform for anybody. If you perform for real people it becomes immediately clear that if you want them to do a specific type of shuffle you need to mime it.
Half the time I see a demo of a trick and the performer says, "Sign the face of the card," the person points with the marker and says, "This side?" Yeah, I know "face" should be obvious, but apparently it's not. Just say "front" or "back."
Bob Cassidy suggests that "only magicians" think it's strange to use the word "billets" to describe those little pieces of paper used in mentalism when talking with laymen. Certainly spectators should be familiar with the "billet reading seances" of the mid-19th century? Well, first of all, I don't think that's quite as common a phrase as Mr. Cassidy imagines it to be. So yeah, it is strange to call them billets. Even the dictionary describes that use of the word as "archaic." Now, to be fair, I might introduce that term to an audience, and discuss the etymology of it coming from the French word for "love letters," because that could be interesting. But just to say, "Write a word on this billet," would be dopey as hell.
These aren't just esthetic points. Yes, most spectator's can figure out what you're saying from context, but there's no reason to not make things as straightforward as possible. And the less people have to do any interpreting the easier it is to connect with them/mess with their minds.
I once heard a magician friend tell his spectator to find her card in the deck and then "outjog" it. The person was like, "What the fuck are you talking about?" but he was already on to his next point. His spectator had no idea what to do and it completely stalled the trick. Afterwards I said to him, "Just tell her to pull the card out an inch or so." He argued that "outjog" is a normal word that means "to pull something out a little." I was almost convinced that maybe it was, I've been stuck in this magic world too long myself. So we googled it and all the results in the first few pages were magic related except one that said one of the Jonas brothers could outjog them and they wouldn't mind because then they could look at his butt. So that's the public understanding of the term "outjog."
Have you heard worse or are you guilty of anything similar?