This one was a little over a decade ago, when plasma TVs were still manufactured and sold, and LCD TVs were still catching in terms of awesomeness.
I was a young, bright-eyed electronics associate working for the big "blue and yellow save money" company. This particular day was a steady but peaceful day, and I was working the counter, cashing people out and directing them to various areas in the department where they could find things.
I had just finished ringing a customer out for a PS3 game when a fella walks up to the counter and the following exchange took place:
Strange Customer: "Hey man... do you sell TVs?"
Me: caught off guard by the question, I slowly turned to the TV wall that sat in full view roughly 30ft away, filled with 30+ different TV models, then slowly turned back to him "Sir, I don't think I can help you."
SC: "Oh alright man, no problem."
And then he just left. It remains, to this day, the most bizarre customer interaction I have ever had, and I would not be surprised if it was a part of a YouTube prank video. I've been at the store I work at for over 13 years now, and nothing has topped this one for weirdness.
Pixel Tablet the Flamethrower! Ah the kids love that one.