LOL ElSanity you idiot! Out of interest, what is gba and ds? Your purse sounds very different to mine! If I was going to a dance I would probably skip all those things (well, if I absolutely had to I would have a small notepad and a mechanical pencil; that way you don't need a sharpener AND you have an inbuilt eraser!), then I would add in 'the basics': wallet with enough money for a taxi home 'incase', tampons/pads (better safe than sorry!), if you are wearing makeup I would also throw in the lipstick and eyeshadow incase you need a touch up, tissues (I would take 10+ but you might be far less snotty!)... oh, and if you are anything like me you will also throw in lipbalm, eyedrops, three different sets of tweezers, nail clippers, nail file, gumnut, gemstone, chewing gum, soothers... yeah, ok, well you asked! 
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...though fire may burn & flames envelop me, I will arise from the ashes...