T.S.
"Twirling into two, so bring your tutu?" I don't know...anything would be kind of corny, but that's part of the fun of HAVING a two year old, isn't it? They will love the silliest things!
One thing...my ballerina got started by falling in love with ballet at two. We we got her into lessons at three and a half. She is now about to turn 11 and is on pointe, going to class twice a week and helping teach a younger class once a week, and has been absolutely focused on becoming a professional dancer since that first class. You never know! This might not be a passing phase.
I love the idea that the mom below had of hiring a ballet student to come show them some moves. It is very easy to make tutus with inexpensive tulle and wide ribbon or blanket edging. You might either make one for your daughter or even make several as the party favors for the children at the party.