The men's and women's bathrooms in the different buildings are identical, but reversed. In other words, they are located in the same spot on the floor, and are directly across from each other, but in one building the men's room is on the left, and in another building it's on the right. If you're not paying attention after moving to a new building like yours truly...
First thought: "Where'd all the urinals go?"
Second thought: "Hmm. It smells like roses in here."
Third thought: "Why is there a little pink sachet in the corner by the sink?"
Fourth thought: "Uh-oh."
And of course I got busted by a new coworker upon scrambling out of there who was kind enough to understand the confusion but I'm sure was thinking down deep somewhere, "Great, the new guy's a perv..."
You've been warned.