Magicians go to a party to help it succeed.
When he arrives at the party and asks the birthday mom for a mirror (because he didn’t bring his own), or a pen (to sign a card), or a lighter (to light the vanishing candle), etc., then he morphs from being an entertainer to being a burden.
Don’t be a burden. The birthday mom has enough on her plate.
She isn’t your guardian angel. Bring everything you need for your show so she won’t scurry around finding those items for you.