teenageloveaffair, Remove the sharp ends of the banana and you will be fine. Make sure it is clean. The best is to put it inside a condom. If you use a peeled banana, the sugar can cause a yeast infection.
There are many other fruits and veggies you can use, like cucumbers. The same rules goes: Make sure there are no sharp edges, wash it well and keep it inside a condom. Don't put peeled fruit inside your vagina, it can cause a yeast infection.
Other things you can use are smooth and clean hair brush handles, water from the faucet or hand shower or small plastic or glass containers like shampoo or beauty products or an electric tooth brush (make sure it is not plugged in). Make sure everything is smooth and clean and that you can get it out. Once again, clean and smooth. And once again, clean and smooth.
The best thing however by far is your hand and fingers. (And once again, clean and smooth.)
Take care.