Basically, because a banana and a penis have a lot in common, some people have associated them with each other. Now, when revealing a penis or a penis-shaped object, it will usually be accompanied with an exclamation of "BanananAAAAHH!"
Leftover remains in a man's beard from eating pussy and not washing your face afterwards. Usually seen the morning after. Appear as crispylittle flakes.
I had some serious banana chips after eating my girl our last night.