Tell her I need to go home and get changed first

I really want to go. Tiffany is by far the most popular girl in the whole school. She is only with the really "hot" people and being her friend or possibly even joining her clique would greatly raise my own reputation.

I take a quick look around the hall and notice that almost all eyes are on Tiffany and me. A few have an envious look and a few seem visibly puzzled as to why Tiffany would act so friendly towards me.

However since it is a party I can't just show up in my school uniform, "Tiffany I love to go with you, but I need to get changed first. I don't think I can show up in my school uniform."

"It's okay, Lisa. I will lend you some of my own stuff. I still have lots of designer clothing that does not fit me anymore in my wardrobe but I am sure you will look super hot in them." she replies.