Its a piece of paper that literally says "tag applied for". If you buy a car from an individual/non dealer you get a certain amount of time (couple of weeks to 30 days depending on state) to get a new tag for it. Until that point you can drive it basically unregistered.
All the ambiguity involving that means you can basically just take off your license plate whenever you want and police dont look at as a particularly unusual or noteworthy thing to run across. Even if you dont put "tag applied for" at all most cops just assume thats the situation and wont pull you over for just that unless you are having some other violation going on.
I had a coworker who was robbed earlier this year and the person left in a car with a you guessed it "tag applied for" paper on the license plate section of their car.
All the ambiguity involving that means you can basically just take off your license plate whenever you want and police dont look at as a particularly unusual or noteworthy thing to run across. Even if you dont put "tag applied for" at all most cops just assume thats the situation and wont pull you over for just that unless you are having some other violation going on.
I had a coworker who was robbed earlier this year and the person left in a car with a you guessed it "tag applied for" paper on the license plate section of their car.