Where did the catch phrase 'whoops have a banana' come from?

Answer

"the have a banana" line comes from a cheery musical hall song in England called "Lets all go down the Strand"

and at the end of the verse the song has a chorus...

"Let's all go down the Strand - have a banana
Let's all go down the Strand..."

on the song i have a lovely bunch of coconuts, towards the final verse there is a follow up with

"i have a lovely bunch of coconuts-lalalalala

everybody throw and make me rich- have a banana"