I used to walk to school through a parking lot and every day there was a car with the plate: BAAB. I could not ifgure it out and eventually gave up. then one day I happened to put two and two together when I noticed the car it was on was a Saab.
Also likely owned by a urologist: WEWE DOC
I still giggle every time I think of that one. 
Tolkien?? 
I haven’t smoked in decades.
I keed! I know who JRR Tolkien was, but I still need the translation
Plates that I’ve seen:
WARSUX (“War sucks!”) - On a car with a Purple Heart plate AND a USMC sticker!
1NFDL (“Infidel”) - On a car with a “Fight Terrorism” plate!
THEBANKS (“The Bank’s”) - as in who REALLY owns the car. Unless the family’s name was Banks.
C1AO 2TI (“Ciao tu ti”) - Italian for “Good Bye to you” (Please forgive my spelling and translation.)
METAD8TA (“Metadata”) - must have been a database person.
AUH20 - Goldwater (Au = Gold, H2O = Water)
A friend of mine, a US military officer with some intelligence experience (and plenty of intelligence of his own), had “I SPY” on one car and “KGB SPY” on his other car.
sigh
“Noro lim, noro lim, Asfaloth!”
Note: I am nowhere NEAR the level of mastery displayed by the venerable Qadgop
Just remembered this story: MPEACHW
OH NOES
There’s a plate here at work: TI GUY
and I’ve seen H2OSKI
The owners of the house across from me have a red corvette. Why do I think there is more than one owner of it? The tag reads “CATHIES.”
seen on the back of a very late model, very expensive-looking cadillac something or other driven by a perfectly-coiffed older woman while driving on I-465 in indianapolis:
IWON
i don’t know the story behind it of course, but i can guess.
wonder what her ex is driving these days.
When I lived in Virginia, I had a plate from the Parrothead series. My number was CDLZRD.
Saw this one last week: GODNME
“Look honey! A real holy roller.” 
AUILOX, on a car driven by a blonde. Took me ages of seeing that every day to get it.
I remember hearing about this one so it may be an UL but somebody had plate:
3M TA3
which is of course to be viewed through someone’s rear view mirror.
On a Lotus Esprit that passed me on the freeway the other day:
IMPOOR (Well, who wouldn’t be after spending $100K on a car?)
I saw a Jag the other day with “IM A VIP”
Oh, and a buddy of mine has “NSTIG8” (instigate).
During the days of the old double nickle speed limit, I saw this delightful comment on a California Licence Plate:
**55 MY A**Not as cool as the ones here, but the last two days I’ve seen a big black SUV with “FREAKY” license plates. Kinda cool!
My coworker has a light green saab with the license plate wasaabi
I thought it was clever on multiple levels.
A couple of weeks ago while driving to work I saw a big motorhome pulling a small car behind it.
The license plate on the RV was IPULL.
The small car had IPUSH.