Tell her you want to get ready at her house because it is her big day,or you just remembered you left something at her house and you need it for the concert,like a bracelet or something.

Either tell her you left something at her house, or have her mom or someone call her and tell her she needs to stop by the house before the concert to get something.

Yea, what brok said. But tell her you left the tickets there. Make sure you stop by her house before she comes over your house so that your excuse seems legit.

Mention you left something at her house

I'm throwing a surprise party for my best friend, and I have to keep her out of her house the whole day. I told her I got concert tickets and she is going to get ready at my house, but the party is at her house. What do I tell her to get her to stop at her house "before the concert"???