Look into Perfumer's Apprentice for a VERY green banana flavor. It's not an
e-liquid; it's not even listed as a flavor over there, as I recall. I think they have one called Ripe Banana (or possibly DIY Flavor Shack), too, but when you go to the molecules and notes section of the site, there is a weird sounding chemical that is extremely green tasting and stupid strong.
The green banana is the opposite of a ripe banana, yes?