How do I get over my fear of waterslides?

In a couple of weeks time, I'm going to Cyprus and my nanna says she's going to take me to Fasouri which a big waterpark. She also says she may take me on the toilet-bowl-style waterslide (where it shoots you out and you spin round and round in a big bowl then drop down the hole). I'm quite scared and queuing up freaks me out for some reason, the anticipation and when somebody queues up behind me I know I'm forced to go down it and there's no way back. How do I get over my fear? Any tips? Please help!