Is you is or is you ain't my stoner?

Mr. Dog has an annoying habit of not renewing his car tabs on any kind of regular schedule.  Two years ago he got pulled over on his way home from the airport after his final visit with his aunt in Chicago because his tabs were expired.  By more than a year.  You'd think the $200+ ticket would deter him from letting them expire again.  You'd be wrong. He's been driving around for the past 8 months with expired tabs.  A few weeks ago he decided to renew them again. After some nagging, he did it and the tabs quickly arrived.  They just never made them onto the car.
Big Dog has an annoying habit of bringing all sorts of crap home from school.  In big plastic baggies.  At the time it comes home it is the most fascinating thing ever.  Sometimes it's something that looks like dentures made by 1st graders, sometimes it is a sculpture made of wire and packing peanuts,  sometimes it's a dissected owl pellet, other times it's junk he collected up off the ground.  We never know, and despite its initial allure it all quickly loses its charm.  They collect up in his backpack until it reaches a critical mass or he needs to dig out the newest discovery.  Then the old baggies of stuff are discarded wherever he opens his backpack.  Sometimes this is in living room or on the dining room table, other times it's the front seat of your car.  You never know where they'll land.
What do these two annoying habits have in common?  Read on.
As I mentioned above, Mr. Dog renewed his tabs but never put them on his car.  Well tonight he got pulled over.  No ticket this time, the officer was able to look him up and verify his registration was current.  And that would have been that, but the cop spotted something suspicious on the front passenger seat.  A big baggie filled with something like bulky lint.  From a slight distance, I'm sure it looked more like dried plant matter if you get my drift.
"What's in the bag?" asked the officer.

The suspicious bag, click on the image to enlarge.

"Um, I'm not sure," Mr. Dog said quickly, absolutely unsure what it was or where Big Dog found it.  And it looked suspicious. Even up pretty close it looked bad.
"Mind if I take a look?" the officer asked.
"No, not at all," Mr. Dog answered instantly, "it's just something my son left in my car."
"Oh really," the cop said as Mr. Dog handed the bag over.
The officer turned the bag over in his hands, mashed the contents gently through the bag then took a sniff or two. Mr. Dog was beginning to worry.  He really had no idea what was in the bag or how it came to be in Big Dog's backpack.  And he had reason to worry, Big Dog's school is in a, um, transitional neighborhood and he could have picked it up on the street.  Really, it could be just about anything.
After the sniff the cop decided it was nothing. "Kids bring home all kinds of things," he said as he handed it back to Mr. Dog.
Mr. Dog headed home still somewhat unsure what his cargo was. What was in the bag, you ask?  You know that dissected owl pellet I mentioned before?  Yeah, that. Luckily that can't get you busted for possession.