One of those lines that I probably heard 50 times before finally being old enough to understand what it meant. My naive little brain was never able to make sense of why they were in bathrobes.
[edit] It was probably more like 20 times and then 30 times where I could have understood it, but was so accustomed to the original, innocent interpretation (they're in bath robes because it's the morning and they just came from home) that I completely neglected the fact that they said "brothel".
Like this: