Lookie Loo

We've all heard the expression "lookie loo", right? Well, the "loo" is the slang term for the bathroom in England, so I wonder if the etymology of the term "lookie loo" relates to the action of watching someone going to the bathroom, sort of like a peeping tom? It would make sense, because it would be somebody who is looking at someone in the loo. And that might explain why it's a sort of derogatory expression to say someone is a "lookie loo".