RCKTSK8 on a Tesla. “Rocket skate”, I assume. I guess that’s a reference to Tesla’s “skateboard” platform, but to me it sounds like something Wile E. Coyote would buy Acme.
DANKAMI on another Tesla. “Ami” is French for “friend”, and from what I gather “dank” is Gen Z slang that has a connotation of “old”. So “old friend” is my guess.
GRAILEY on a BMW sedan. A name, I guess?
“Dank” is also slang for high-quality cannabis. So, I might guess that it’s someone who likes pot. 
Looks like a senior was issued an … umm, interesting plate in Florida:
The link is to a video, but I think the little bit posted here will tell you all you need to know.
ALL PJS - maybe the whole family has the same initials or they just like lounging around in their pajamas.
I love it! Great find!
In a similar vein just yesterday I happened on a 4-door Jeep Wrangler with New Jersey plates that said S50 WPH. But with my brain’s personal plate recognizer now permanently turned up to eleventy I read that as 250 MPH. And I thought “Only in your dreams buddy!” 
Then I noticed my mistake. 
In a very slightly similar vein my late wife was once issued a series plate that read H8T #X# where I don’t remember the last 3 number-letter-number. It pissed her off that her plate said “hate” on it. But of course all the other plates in the clerk’s drawer that day were also “H8T something else”, so she was stuck with it.
Here’s a few from my last couple days that really are custom:
J⎵COWBOY on a FL standard plate on a shiny clean gray Ford Maverick 4-door pickup. I got a good look at J. Seems like a 30-ish workin’ class fellow with a well-worn baseball cap. I could see him working with horses or cattle. But unless the truck is brand new, it’s never been rode hard nor put away wet.
DOMUNIQ on a 7-character FL breast cancer booster plate on a midrange Mercedes sedan. I like the overlapping words effect; very clever.
W4ANA on a crossover. Which I was having trouble parsing until I saw it was the FL amateur radio booster plate and so that must be their call sign. I tried using @DesertDog’s Ham lookup site, but apparently you need a membership to see much beyond confirmation it’s a legit US license.
On an older, red Corvette: IOWNR91.
It might be how public the entry is. While the guy’s page had what you see his wife’s callsign yielded the must register notice. Guess I was lucky.
Got some more today.
DEXTR on a FL 5-character veteran booster plate with a Viet Nam Veteran frame on a Nissan SUV. Dexter was in his parked car, and he seems to have been a veteran of the later part of the war. Looked to be aged early 70s to me, not early 80s.
NLC⎵⎵⎵1 on a FL standard plate on a generic crossover. No clue. it wasn’t parked in front of anything with a similar name.
SEMYAJ-1 on a FL standard plate on Volvo SUV. SEMYAJ is JAYMES spelled backwards. Which would sorta kinda work for looking at his front plate in the rearview mirror. Except FL doesn’t have front plates. Maybe the 1- shuld be interpreted as “I am”. Or just “I Jaymes”. You Tarzan, I Jaymes. 
I also sighted a couple more that I’ve cited upthread at some point, so I’ll skip them here.
Saw several today, but can’t recall them all
QTRMIL – Runner, I assume
LOCKD
YUGIOH – on a car that had “Just Married” written on it. I hope they’re both manga and anime fans,
Or drag racer or fan.
It also a popular distance for quarter horse races.
Or, possibly a drag racer (or a fan of it), as many drag race tracks are a quarter mile.
KTO GOLF
GEEDUB3 on a BMW
GEL00F
Some guesses but no real idea on any of them.
NVRMYND
OK, I’ll ignore it.
A big, black SUV: PHRIEND,
A grey (British, so not ‘gray’) Jaguar sedan: LEFRANC, and
An older Mustang with: LAILSON. A name? Dunno. I’m pretty sure it’s not a note on the availability of a certain approach to LAX. 
On a late-model Audi:
STRUDEL
A Polestar II with the plate AIMBOT.
RAMA 17 - could be a name or an avatar of Vishnu.
VASILII on a Lexus hatchback thing. Upon Googling it, I learned that that’s a name in some cultures.
Last night and this morning I spotted:
YOURCAT on a Tesla. How do they know I have a cat? Or maybe the driver’s nickname is Cat for Catherine.
JEEPB2U on a Jeep Compass. “Jeep be to you” I guess? That seems a little nonsensical, but ok.
HAPYLTE on something forgettable, with a frame advertising happylite.com. I guess that must be a business they run, which appears to sell therapy lights.
Took me a few days to build up enough to bother with, but here we finally are:
GRAMEE⎵4 on a FL standard plate on gigantic Infiniti SUV. I bet she can carry a lot of seething grandkids in that thing.
CHEERO on a FL standard plate on a generic car with a bunch of feel good be happy bumper stickers. They might be fun to have for a friend.
LORYN on a FL 5-character Miami Heat NBA booster plate on a crossover.
SANDVL5 on a FL standard plate on a basic white pickup truck. Didn’t look like a company truck; just some guy. Probably last name Sandoval, but I prefer to think it’s something more interesting like Sand Devil.
BLK⎵PAN on a FL standard plate on a Tesla Model S. The car was wrapped in a dark gray matte finish and did pretty well resemble a hard anodized non-stick pan like these Calphalon frying pans.
USA⎵VIP on a FL standard plate on a black Mercedes SL550 convertible. The driver was a gray haired executive / recent retiree lookin’ dude. Some Googling now suggests he might be a honcho with the Florida branch of these folks: Travelink USA VIP - Premium Transportation Services.
NOTM8 on a FL 5-character Gadsden flag RW tax protester booster plate on a red Corvette. Maybe he was unhappy with his prior BMW M8 and traded it for the Vette? Maybe he also has an M8 whose plate is NOTVETT? Maybe he’s also an MGTOW and is real proud to not have a mate = wife / GF / SO?
SCERB on a FL 7-character breast cancer booster plate on a VW Tiguan SUV. I had no clue at the time, and did not get a look at the driver. There’s no medical clinic or similar around here with those initials. Some Googling now suggests there’s a guy who’s a financial advisor and a woman who’s a massage therapist both with that last name who live / work near where I saw the car. No clue which I saw, or whether those two Google hits are related in any way.
EVERICK The frame had I [heart] my Bichon Frise so maybe it was the dog’s name.
