name + catchphrase/slogan for my event?

Hi all, I'm designing a poster/flyer for my school event.



basically it's an event promoting going green, where students collect water bottles around the school, and they can come to me to trade for a prize. the more bottles they collect, the bigger prizes they get



I need a name, and a slogan for my event. or also things to put on my poster that grabs students' attention. Thanks a lot :D