There was one I remember from years ago that was an impossible to remember combination of seven characters of the letter ‘I’ and the number ‘1’.
Today I saw AEIOYUU
Must be a vowel lover. Maybe a vowel lover named Yu.
I had a coworker and her name was Yu. I’d always greet her with a, “Hey Yu!”
But she also went by Jade, so there’s that too.
Yes it really was.
ORCARU on a white OBW, a Subaru Outback Wilderness edition. With its extra black plastic cladding, a white Wilderness edition of the Subaru Outback does look like an orca.
The ORCARU plate is a clever one. These are web pics.
Like this you mean:
Hover-over:
The next day: ‘What? Six bank robberies!? But I just vandalized the library!’ ‘Nice try. They saw your plate with all the 1’s and I’s.’ ‘That’s impossible! I’ve been with my car the whole ti-- … wait. Ok, wow, that was clever of her.’
from xkcd: License Plate
Or a fan of yodeling.
Saw SASSI on a Tesla (natch) in the grocery store parking lot.
Saw this yesterday, took me a moment, particularly because there were no bumber stickers or decals to help: FGTNIRSH.
Fightin’ Irish came up instantly in my mind and I’m not even a football fan.
The driver of the Toyota ahead of me this morning was a real LYONTMR. So either a fan of big cats or a French clockmaker.
I started with FGT as “fuggit” (IOW fuck it) and then as “forget” as in fuggedaboudit Sopranos style. So “fuck it nirsh” or “forget nirsh”.
When I couldn’t make sense of “nirsh”, that’s when I moved the N up into the first word for “FGTN IRSH” and it became obvious. But I had a few seconds of tussling with “FGT NIRSH” first. 
Saw three yesterday:
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M⎵TRAIN on a standard plate parked outside a gym. “M” wasn’t part of the name of the gym so I suspect a trainer working there named Mike or Michelle or something. I don’t know of a training regime named “M”. The “M” might represent “me”, but I still prefer it as a first initial.
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MIAMI⎵MK on a standard plate. I guess he’s named Mike. I didn’t see the driver.
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NTITY on the 5-character University of Miami booster plate with the big orange and green U as the left ~25% of the plate. If we include the U in the word, it just might be “untidy” or even “untitty” for a woman proud of her sleek high speed boyish torso. But most likely it’s just “entity”. But why a plate reading “entity”? There’s the mystery.
Maybe the owner liked Tina Turner in Mad Max Beyond Thunderdome. 
I love Tina Turner’s music. I enjoyed the Mad Max movie series. I have no idea what connection there is between that and “entity”. But when it comes to pop culture allusions I’m mostly a Klingon. Sorry. Care to enlighten a poor interstellar traveler baffled by human entertainment?
I just came back from a 20 mile road trip across suburbia where I scored about 6. All interesting; nobody’s initials. Of course I had somebody cute in the car with me, so no time or attention span to take pix or notes. And now I have exactly zero idea what any of them were. But trust me, they were good ones. 
Turner’s character in Beyond Thunderdome was named Aunty Entity.
ROCKBZ on a work truck, I assume for a masonry firm.
SCOTUS weighs in:
Figures it’d be Tennessee.
Thank you. I eventually noticed that the big U on the plate background could make the whole thing read as “Untity”. Which is not far from a contracted elided “aunt entity” with the “aunt” pronounced more in the black “awwnt” style than the white “ant” style.
For the small amount of driving I’ve done so far today, I had quite a large haul. Some good, some meh.
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IGOVOLT on the standard plate on a Tesla Model Y.
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W2IIH on the standard plate on a Tesla Model Y. They had an “I’d Rather be FLYING” license plate frame. Flying or no, I have no clue what that plate might mean.
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PN4TZ on the 5-character surfer booster plate on a pickup. It’s probably just an ordinary series plate, but at first I thought it might be a creative respelling of “peanuts”. Whether the nuts or the comic I cannot say.
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CATMILF on the standard plate on a small SUV. Color me quite surprised it got past the censors. But I was standing in the parking lot looking at it parked there. I definitely did not mis-see it.
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GLAMMA⎵J on the standard plate on a generic white Toyota sedan. I’m interpreting that as “grandma somebody with first initial J”. Maybe she’s an extra glamorous grandma, but the car suggests no.
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1⎵⎵CCR on the standard plate on a BMW X3 small SUV. CCRs are famously the “covenants, conditions, and restrictions” common to HOAs. And to redlining back in the day. It seems like half of SoFL sells real estate and the other half lives in HOAs. So that might be it. But I’d rather bet this was simply somebody’s initials.
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1⎵⎵LSA just a couple minutes later on the standard plate on a shiny Hyundai sedan. Almost certainly initials.
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GAA on a standard New Hampshire plate on a Subaru Outback. Probably just initials, but I’d prefer to think it was really a primal scream and Gaah! was already taken.
Or, maybe, the really well-known rock band which is frequently referred to by the initials CCR.
To me “M Train” sounds like a New York Subway line. But I have no idea if there’s an actual M Train in New York, and I can’t be bothered to check right now.
ETA: I lied. I had to look it up, and there is indeed an M Train in New York.
Looks like a ham license to me.
Mmmm, ham drools.
(Yes, I know you meant “ham” as in amateur radio operator).