this skin should be created i mean as she has a weapon that throws out like a blade it can be a boomerang! and her ultimate as her surfing around summoners rift! her w as a life guard hoop when she throws it at champs and minions! her e should be made out of water! 
If i had the chance to edit her i would but i dont have a way of doing it! please think before you vote!
I think Pool Party Sivir should just be her throwing a floaty ring thingy. http://i.istockimg.com/file_thumbview_approve/12667994/2/stock-photo-12667994-bright-floaty-ring-in-rippling-blue-pool.jpg
Then her Q just throws it, her W just bounces it, her E is a water shield (I like it), and her ult (also like it) makes everyone surf.
And, of course-of course, Sivir is wearing some Summer attire appropriate for water sporting c:
Uhm...the idea isn't bad but the execution is lacking. Her weapon is a boomerang-like blade. And frankly, I don't see what relation a boomerang has to a pool party. Overall you're asking for a lot of particle effects and animation changes, and I honestly don't think Sivir needs more skins at this time. But the idea isn't too bad.
