First of all we know the shape of the banana is erotic. A no brainer. But beyond that bananas contain nutrients, including potassium and B vitamins, essential to sex hormone production. Bananas also contain chelating minerals and the bromelain enzyme said to enhance male libido. Central Americans drink the sap of the red banana as an aphrodisiac. The Hindus regard it as a symbol of fertility and a banana left on a doorstep indicates that a marriage (I'd say consummation, but hey) is about to take place.
However, the banana might be the reason we are all here. According to Islamic myth, it wasn't fig leaves that covered the nether regions of Adam and Eve, it was banana leaves, which also happen to have a very phallic shape. One school of thought says they began donning the banana leaves after they succumbed to the apple. Another, that the banana itself was the forbidden fruit they indulged in. Either way they had a lot of fun playing 'hide the banana' (salami wasn't invented yet).
The Well Heeled Cook recipes that include bananas: "Dessert as the Main Course" - banana split with chocolate hazelnut ice cream.