Names omitted to protect the innocent[*] (no sense trying to disguise the guilty, as y'all would just guess anyhow), and because the quotes-from-memory are probably not remembered quite right:
"If I have to resort to linoleum flooring, it'd be cool to have something other than a solid colour or geometric patterns or woodgrain. A custom image covering the floor instead."
"Oh yeah, I've seen something like that."
"So when a guest steps into the living room, suddenly they're standing on the edge of that pit on Tattooine with the monster in the bottom." [looked up later: the Great Pit of Carkoon, housing a Sarlacc]
"What?! No! Wrong! Bad! NO! Why would you DO that to your FRIENDS??"
"Or maybe molten lava with the most frequent path through the room done as stepping stones? Or a lake and stepping stones."
"Okay, that's better..."
I can describe and thus spoil this next idea, 'cause I'm never going to have the resources to pull it off ...
I'd like to build/remodel and decorate a house such that two rooms are exact mirror images of each other, down to replacing the outside windows with high-resolution video displays so the views from each room's windows match. And cut a hole in the wall between the rooms and frame it like you would a wall mirror. So that I could stand near the "mirror" and wait for guests to move to where they would be able to see my reflection if it were really a mirror, and see who notices that I don't have a reflection, and how they react. Or maybe just wait to see who notices that they don't have a reflection.
(If I frame this as a psychology experiment instead of a practical joke, could I get grant money to build the rooms?)
[*] Never mind the gestured toward anonymity --
says I got the conversation close enough.