My mama told me, If I was goody
That she would buy me a rubber Johnny

The story:

(for those unaware - a rubber johnny in England is a Rubber in the usa - condom!) - I had heard it someone singing this at school and thought it was the real line. I was watching Top of the Pops with my grandparents and started singing along - when it got to the line - i thought my gran was gonna have a coronary....they both looked at me in shock - i of course did not know what it meant at the time......My brother explained it to me later!!