Getting Mixed Signals...Don't know what to do. Advice?

So, while I was in French class, this girl turns to me and asks if I wanted to go to Homecoming with her. I said yeah, and laughed, thinking it was a joke. Though now, I'm not too sure. She's been going around the school and telling everyone we're going to Homecoming together, and every time she sees me, she screams "Hey, look, it's my homecoming date!!" Although, this isn't what caused the confusion. Earlier this week, I went to her volleyball game, and she asked me to paint her number on my face, so I did. After the game, she comes up to me and we're talking and I jokingly mentioned that I would paint her number on my stomach the next time. Then, shes says, "Oh...even if a BOY asks me to homecoming?", and just sort of laughed and said yeah:dry Edit - Later on that day, I heard that she was waiting for this guy in her class to ask her to Homecoming because she has a crush on him). In spite of this, she's still going around and telling people that' we're going to homecoming together. She's even used me at times to turn down other guys who've asked her. Then just today, she called me over and asked me to prove to a mutual friend of ours that we were going to Homecoming together. So, yeah, super confused.:help: