This sign is posted in Knit-A-Way, a yarn store in Brooklyn.
Let me start with the good:
I appreciate the store owner's attempt to define "shoplifting" for people who are both larcenous and retarded. You need money AND permission if you want to walk out of this store with yarn.
If you have permission but not money, it means the clerk is giving away free stuff, which makes the store owner cry.
If you have money but not permission, it probably means you did something offensive. Like, if you tell the clerk you want to spend $20 on this yarn and she tells you to get the hell out and take your pet monkey with you, you're going to have problems. Put the yarn down, leash your monkey to a hydrant, and try again. She still might not sell you the yarn, in which case leave and try somewhere else. There are lots of yarn stores in New York. One of them is bound to accept monkeys.
If you don't have money or permission, stop. Put the yarn back on the shelf and walk away. You are about to commit a crime.
Now for the bad:
Shoplifting is not a federal crime unless you are on federal land, and the Knit-A-Way on Atlantic Avenue is not federal land. It might also be a federal crime if you steal $600,000 worth of scrapbooking supplies and try to sell them online. But this takes the kind of commitment you probably don't have.
This sign is a fat, sweaty liar, and lying is rude.
In most cases, shoplifting is a state misdemeanor. Laws vary from state to state, but in New York, if you manage to stuff more than a thousand bucks worth of yarn into your pants, you might be charged with a felony. That's not the same thing as a federal crime. The only way this becomes a federal crime is if you steal half the yarn in the store, kidnap the clerk, drive her to Las Vegas, sell the yarn on the black market and smash a bunch of mailboxes on the way. Please don't do that, because the clerk at Knit-A-Way is a nice lady who probably just wants to go home, have dinner and watch "Wheel of Fortune."
Shoplifting is still a shitty thing to do, so don't take stuff without money and permission.