“Hey man, you see these condoms on the ground? They’re used, man! USED!”
Somewhere in VA, the judge swapped robes - white barber’s robe for a black judicial one.
The proctologist & psychiatrist who went into business together - Called their practice Odds & Ends.
Grabs own shirt collar & bumrushes self out the door
In the 80’s in Lexington KY there was bar with a open archway in the shared wall to a large hardware store next door.
My current eye doctor’s office is half optometrist office/half hair salon. It’s a bit odd.
A ferreteria?
(hardware store in Spanish, not for ferrets!)
Recently, in our small town, “Andre’s Electronic Experts” built a large new building. I supposed they would sell electronics and they do, TV’s, sound equipment, and large appliances. That only uses part of the building, the rest is devoted to"Andre’s Carwash", two self-serve bays and two automatic carwash bays. and one vacant storefront that is for rent. This is not a mom and pop business but a chain that operates in many western Canada cities. 
Slightly off topic: I once drove past a strip mall in the L.A. area, where the back of the stores faced the highway and, while I’m sure the front of the mall had distinctive signage, the side facing the highway had short signs describing each business generically.
The upshot was two signs abutting each other, in the same typeface: “Mexican Food Cleaners”
Up until recently, in Milwaukee, we had a store that did video rental and tanning. My guess was always that the owner was one of those people that probably sold a little bit of everything and got a good deal on a tanning bed.
Like the OP, I used to work at a motorcycle shop that had a junk-mail printing/mailing business in the back. It actually made more money than the franchise motorcycle dealer!
I can tell you about a place that does exotic livestock, microbrew, novelty hosiery and foreign car service, but the name escapes me just now…
Realtor/dentist/birther lawyer Orly Taitz.
I’m from West Virginia, where a friend was once associated with a preacher whose church was housed in a filling station, which also housed a religious radio station.
Checkpoint Charlie’s, Igor’s Lounge, and Igor’s Buddha Belly are all combo bar/laundromats in New Orleans, although I kinda think it’s a good idea.
There have been a lot of those over the years. Not sure why.
Now that I think about it, there’s a little hole in the wall antique store in my town that doubles as a flooring store. Not sure how much of each they do, but apparently it’s been in business for several generations, one way or another.
One of my customers is a tax preparation business… that also sells high-end luxury French soaps.
Military surplus store and art gallery.
That has always been par for the course for the Captain Video chain around here.
Wine kits and wine making supplies are often sold by florists, for some reason.
I’ve been to Smoke n’ Guns. They sell cigars and have a cigar/coffee bar, plus they sell guns and ammunition.
After all these years, this one still cracks me up. Near my high school there was a combo bait shop and pancake house called, Bait and Cakes. Call me crazy, but I never was tempted to eat there.
In what I thought was a genius move, at the time that tanning salons were all the rage, a local laundromat chain put tanning booths in all of their locations. You have a captive audience, largely female, who have nothing to do while they wait for their clothes to spin round and round. Plus the demographic wasn’t necessarily one that was overly concerned about the side effects of tanning. Once the tanning thing started to die out, they replaced the tanning booths with manicure/pedicure stations. Everyone was happy and the places were making money like crazy.
A few years ago, out in the middle of nowhere and with a hungry family to feed, I pulled in to the first restaurant I saw. It was a BBQ place/antique store/towing service. The BBQ was some of the best I’ve ever had and the antique store had some cool stuff. Fortunately, I did not have to try the towing service. I’m sure it was top notch!
There is a bicycle shop in Albuquerque that has one counter-case filled with reloading supplies.
I worked for a guy that was in the water utility equipment business, and also operated a gravel pit. One day the gravel pit guy had an emergency, so I took a day off from my engineering/programming work, and wrote tickets in the scale house.
At an computer/electronics company I worked for the president added up the commissions he was paying travel agents, and bought up a failing travel agency, so we were an engineer, build to spec electronics company, and a travel agency. The electronics end of the company went through a couple acquisitions, but I still occasionally hear radio ads for the travel agency.
I got my first FAA flight physical from an oncologist. She said she loved doing the flight physicals as a sideline because they were the only patients she had that were not either dying or in fear of dying in the near future.