Where did the expression "asking for a friend" come from?

I've heard it floating around since I was young. It was pretty much always associated with the assumption that the 'friend' was a slightly unsophisticated cover for themselves. In counselling in the past people would do this with me - not necessarily using the exact words. They, often younger people, would talk about a friend that needed help. When they realised I was safe, they would admit it was them.