Misplaced Hostility

I am an art guard but I like to tell people I'm in security. It's one of those "white lies" that seems to be fully acceptable. It's kinda true.
Last week a young, well dressed couple in their mid-twenties came into the gallery where I was conducting surveillance. They looked around a bit and glanced at their map of the museum. I observed the all too common appearance of confusion on their faces.
Male: What gallery is this?
Me: Seven
Female: Seven?
Me: (a more authoritative) Seven.
Male: Seven? (Cocks his head slightly)
Me: Seh-ven.
They shuffled out and went on their way.
There isn't a Gallery 7. There is a seventh floor, which is indeed where I was, but no Gallery 7. Gallery 7 is actually a corporate sponsored gallery and so in turn, bears their name.
I didn't even lie to them purposefully. I had one of those completely brain dead moments. I felt like an ass but nonetheless laughed maniacally about it afterwards.
Remember in 7th grade when the older kids would send you to the boiler room because they serve ice cream there after school on Wednesdays?