After writing this list and leaving this intro until the end, I've to come to realize I define a jerk as someone who is selfish, insecure and rude.
1. Jerks share their crap instead of quarantine it
If you have a good day, you share your joy with others and hope to spread it around. If you have a bad day, you try to not burden everyone else with the details and do your best to compartmentalize and quarantine your gloom.
Jerks will ruin your day with talk of how their day was ruined by a jerk.
2. When a jerk is losing a debate, he slips in an insult so as to not lose more face.
You: I realize you feel strongly that 3 +4 = 11, but so far you have failed to prove to me how that's correct, that's all I'm saying.
Jerk: Yeah? Well, maybe if you spent less time with your fat, mustachioed girlfriend you'd be better at math, I guess.
3. Jerks are habitually late
Habitual lateness kinda implies the jerk doesn't have as much respect for your time as you do. Seeing as how one loose definition of a jerk could be, someone who is more concerned with their needs than yours, lateness is kinda jerky.
However, for the VERY rare breed of non-jerks who are never on time, here's some recommended reading about the psychology of lateness. Or I guess it's recommended reading for anyone, really.
4. Jerks may be aware of social norms but are confident their cuteness/charm/twerking prowess makes them an exception
In college I had a roommate who, when I owed him any amount of money, would hound me for it. If I had the dimmest aura of cash around me, in he swooped:
"Oh, you had money to hit happy hour- so you have my $30?"
"I'm about to go out for the night. Do you have that $40 I lent you 43 minutes ago?"
As most college roommates and friends do, we found ourselves lending each other money a lot- either at a bar, or fast-food place, or with house utility bills, so it was literally an everyday thing and never became a big deal.
But I noticed that when I'd ask him to repay his debts he'd flash what he thought was his million-dollar smile and try to charm me out of it, with, "Ohhhh, come on, you know I'm good for the $20 I owe you. Although... remember when you spilled pasta sauce on my couch? That was at least $20 in damage right there. I'd say we're technically even.....".
But if I tried to weasel out of a payment with him in a similar fashion, he would have none of it. His actions implied that his sharing-among-friends ethos was, "What's mine is mine. But since we are friends, what's yours is ours because friends share", and that when I talked to friends about him thusly, "I always get paid back. But with Greg, I just let it slide cuz, ya know, I mean it's GREG afterall. God, I love that guy".
5. Jerks conflate boneheaded mistakes with a lack of intelligence
"I once saw that moron once put a plastic plate in the microwave. That kinda dumb crap makes me wonder what kind of heart surgeon he really is, ya know?"
6. Jerks think friendship is a one-way street
Jerks assume the mission statement of your friendship is such that you always agree to go out of your way to improve the quality of your friend's life whenever asked- cuz that's what friends do. However, reciprocation involving THEM having to help YOU improve your life shall be viewed as a luxury and is nothing to get used to. And if it does happen, get ready to hear about the inconvenience it was.
Example: Making every hangout session into their ideal hangout session regardless of the desires of those around them. If you are stuck at the in-laws on Sunday and wish you were at a sports bar with the dudes,the non-jerk would play by the rules of the house and prevent the urge to convert 2 cushions of your mother-in-law's couch into a makeshift sports bar while making a pyramid of empties on her coffee table.
7. Speaking of jerks and streets, jerks do the following while driving on the highway
Let's say, you're in left lane going 70, there's a semi in front of you in the right lane going 65 and a jerk behind him is doing the same. As it becomes clear you're about to pass the semi, the jerk juts out in front of you so he can make pass the semi first, making you tap the brakes while doing so. Then he goes right back to the right lane and does his jerky 65.
Sure he could've let you maintain your rate of speed and not tap your breaks, but then he wouldn't have been first to pass the semi.
8. Jerks make every conversation about them
Say your friend talks for 25 uninterrupted minutes about Dave Chappelle and how great his stand up comedy is and how cool he seems. After letting your friend finish you say,
"I actually met Dave Chappelle at Arlington Park last year and we gambled and drank and B.S.'d the whole day. Both of us made a couple thousand bucks betting the ponies that day because he knew an owner of one of the horses. That was wild and awesome day. "
Instead of saying, "No way! That sounds awesome. I love that guy!!! What's he like??!", your friend replies, "Yeah, I've never been to Arlington but I always hear it's pretty".
Another example is when they're not participating in a discussion about which they know nothing. Instead of patiently waiting for the conversation to end and changing the subject, the casually lob in this remark, "Guys, NO ONE CARES about that topic!!".
But they never do well answering your follow up question of, "If you're right, how do you explain witnessing a conversation between TWO people who care about it?"
9. Ask you for a stick of gum
Even though they have a pack in their pocket.
10. Interacts with kids and/or pets to impress adults
When a non-jerk interacts with a kid, it's usually for the obvious reason- to get to know the kid, or help them out, or just spend time bonding with them.
But when jerks interact with a kid, they rely on tired, age-old tricks to prove their superiority to the kid, for the amusement of his adult jerk peers.
If a toddler is shooting a toy basketball at a toy hoop, a nice adult rebounds for the kid while praising him, a jerk blocks the shot then looks around to see which adults were impressed.
Jerks also love scaring household pets to get a good laugh.