This is a story about a person I've known for a long time. Let's call her... Tatu.
Several years ago, we were visiting our local Target. We spent an hour or two exploring the many wonders that Target has to offer, then made our purchases and left.
In the parking lot, Tatu abruptly stopped walking. She stared down at her feet.
"Oh my gosh!" she said.
I followed her gaze. Her flip flops were on the wrong feet.

Note: These are not Tatu's actual feet. This is just an illustration.She'd just spent an hour or two walking around in public without noticing the extreme awkwardness inherent in oppositely placed footwear.
Another note: Tatu is a grown up.
After we got over a moment of paralysis, we laughed uproariously.
Fast forward to present day.This weekend, Tatu came to visit me. She drove in on Wednesday after a five-hour car trip from a place we'll call Dend, Poregon. She arrived wearing a jogging/traveling suit that had black pants and a navy jacket.
On Saturday evening, as she was preparing to take off for Dend again, she put on the same jogging/traveling suit.
In the parking lot, Tatu abruptly stopped walking. She stared down at her jogging/traveling suit.
"Oh my gosh!" she said.
I followed her gaze.
I didn't notice anything unusual.
"What?" I said.
"My pants and jacket are different colors!"
"Yes, they are. So?"
"Did I accidentally steal your jacket?"
"No, it's yours. It's the same one you came in, I think."
"What??? I thought I was matching!"
We laugh.
"Dani, can you believe that I was wearing this all that time and I didn't notice that my pants and jacket were two different colors?"
I think back to the flip flops and many other instances of similar behavior.
Yes, Tatu. Yes, I can.