the opposite of cool bananas, the phrase is said to have developed in scotland similair to cool bananas and has a link to the east coast, a student who usually used the term cool bananas expressed dissapointment and lost for words said rotten bananas and the phrase has spread since. rotten bananas is said when something is not cool, bad news has occured, or dissapointment has happend.
I could not get us tickets to the concert
"awww thats rotten bananas"
My hen just ran away
"unlucky man thats rotten bananas"