The tendency of "evil" to include not just major acts of villainy and attempts to take over/destroy the world, but also generally being an utter dick. Some examples include:
Kicking dogs (maybe literally).
Being rude.
Throwing the kids' bike on the roof.
Securing a high reward for their actions, and then forcibly shaking down their "customers" for even more afterward.
Ignoring people who are injured, homeless, or otherwise down on their luck.
Starting/escalating interpersonal conflict for fun.
Using racist, sexist and/or homophobic slurs.
Stealing the complimentary items from their hotel room.
Working themself into a murderous rage at the slightest provocation, irritation, or inconvenience.
Exacting terrible revenge on anyone who does anything to slight them, no matter how minor.
Murdering people who irritate them.
Lashing out at people who point out their flaws/mistakes.
Being a douche to other villains.
Mocking people for being depressed/traumatized/suicidal.
Rejecting a person's sincere apology for even the smallest of mistakes, and punishing them (brutally) for it.
Being dismissive towards those who lament on their traumas.
Gallivanting around thinking they are the only worthwhile thing in the world, whilst the rest of the population should be in awe of their presence.
Killing or hurting henchmen for no reason.
Taking someone else's food. Bonus points for eating it in front of them. Extra bonus points if the person they stole from is poor, and EXTRA bonus points if the person in question is a kid, such as taking candy from a baby.
Rationalizing vague excuses for insensitive and callous demeanor.
Stating the fact that they have no remorse for the cruelty they have done.
Blaming others for their cruel actions, including their victims, believing that their cruelty is an acceptable response to an unacceptable provocation.
Taking credit for the accomplishments of others. Bonus points if they expect recognition for "their" accomplishments.
Vandalizing the bodies of the deceased.
Mocking those who lost their friends, loved one's, and pets.
Gloating over their murders in front of their victims' loved ones.
Being extremely immature and throwing massive tantrums when things don’t seem to go the way they plan.
Killing themselves right in front of someone just to spite or screw them over.
Expecting exclusive treatment, including from the very people they treat like dirt, for little to no reason beyond their sense of superiority.
Jaywalking.
This is when you have a villain that slaughters a village, bombs a country, murders the president... And then picks a pocket, trips an old lady, sticks a kick-me sign on a police officer, takes someone's parking space, and cuts in line at a fast-food place.
They're not just evil on a large scale; they're evil on all the tiny little details of everyday life they might experience in any possible situation. This trope opposes Affably Evil and Evil Is Cool — this villain is just a colossal pain in the ass, even leaving their alignment out of the question. And often, they get a kick out of being a pain. And it must be pointed that petty motivations do not take from the cruelty and malice of the acts — in fact, they are just as likely to lead past the Moral Event Horizon, and may even make the villain more hated to the audience than they would be otherwise, as there is nothing grandiose or admirable about him. They are just a scumbag of a bully. More often than not, it is a trait of a Psychopathic Manchild or, even worse, a Complete Monster.
In video game settings with a Karma Meter, this means that being classified as Evil requires not just being uncaring towards people, but going out of your way to be nasty in any circumstances - an unfortunate side effect of there being an in-game benefit from reaching particular levels of evil. When maxing out your Karma Meter gives you a stat boost, you're strongly encouraged to do every little act of evil you can to get there as quickly as possible.
May overlap with Hate Sink, a character massively despised for actual villainous actions; and Jerks Are Worse Than Villains, where a jerk is disliked by the audience more than the actual villain is. Contrast with Poke the Poodle when all the supposed villain does is something actually harmless — they don't do anything overwhelmingly evil, but frequently behave like a mild dick to maintain their Villain Cred. See Harmless Villain for someone who lives for doing this.
An opposite trope is Affably Evil, in which a villain genuinely behaves in a very pleasant, friendly, and/or downright honorable manner. The Magnificent Bastard always avoids this trope; magnificence and pettiness don't mix.
See also For the Evulz, Card-Carrying Villain, The Devil Is a Loser, Even Evil Has Standards. For examples where a petty action ends up harming the villain, see Dick Dastardly Stops to Cheat, The Dog Bites Back, and Stupid Evil. If the villain manages to keep his reasons secret until the climax and the protagonists act stupefied at the discovery of such a petty reason, see Disappointed by the Motive. Badbutts can have similarly petty motives.
