This is somewhat similar to the posting about the 'Plantain', but it has its differences:
Take a large banana; large enough for your cock, and cut off the end (end of the banana, NOT your cock!!! That would pose serious difficulty in performing the rest of this!). Carefully extract the banana, keeping the peel intact. Warm the peel in the microwave for 5-10 seconds. BE VERY CAREFUL! These things heat up like jelly doughnuts and get very hot very fast. You don't want to do any damage! Slide your cock into the banana peel sleeve and jack off. Soon the banana oils will coat your cock and you'll get the smoothest, most natural lube you could ask for. It's like a fantastic, tight, oily cunt, but it's all done by hand! You'll love it.