Slighting is a practice as old as mankind yet insufficiently updated for our online selves. You probably care about your relative status way more than you're willing to admit, but you're not above this game. While egregiously petty, here's a handy how-to on subverting your friends, acquaintences, and rivals while keeping face:
BLOCK A FRIEND'S POSTS FROM YOUR TIMELINE
Discrete. Safe. Low-Risk. (Snub rating: 1 out of 5 noses thumbed in the air)
Whether it's because he shares things way too often, or because his incessant humblebragging is making you feel shitty about how you haven't done anything cool in a while, the great part about hiding a friend's posts is that you have little chance of being called out on it; Facebook's news feed algorithm is utterly & deliberately incomprehensible. A convenient scapegoat if you do get caught, but it won't get to that point. Don't feel bad about doing this.
RESPOND TO A GROUP EMAIL CHAIN, OMITTING ONE PERSON
You sneaky devil. (Snub rating: 3 out of 5 knowing laughs to yourself)
Nothing gets more in a person's head than actually starting a conspiracy against them, and removing someone from a group email thread to talk shit behind their back is exactly that. It's a risky move to try within your clique; be sure that everybody already hates this person before trying this out.
NOT FOLLOW SOMEONE BACK
A little petty. (Snub rating: 2 out of 5 snide remarks said while averting eye contact)
If someone you know has taken the time to find you on this site, and you don't return the favor by just pressing the button to follow them back, then you're instantly a little bit more important than them. It's the kind of thing the other person wouldn't bring up because it's too stupid to appear to care about it, but that's exactly where the genius lies... and you know that. You petty bastard.
CROP OUT OF YOUR PROFILE PICTURE
Ouch. (Snub rating: 2.5 out of 5 hugs that you actually didn't mean)
Your whole vibe isn't what I'm going for, but unfortunately I look really good in that picture we're in together. So I'm cutting you out of it, even though both you and I know you're in the picture. Much like other slights on this list, one has plausible deniability against being confronted on it: blame the aspect ratio. "Yeah, if I included you, it just wouldn't have fit the proportions of the site. They want it square now. Weird, huh?"
TAG THEM IN PHOTOS WHERE THEY LOOK TERRIBLE
Gotcha, bitch. (Snub rating: 3 out of 5 pegs sufficiently taken down)
This is a great slight to pull. The few people that are actually okay with how they look on camera set an impossible standard for the rest of us, who have trouble pulling off that cool, casual, off-the-cuff look, who insist that we're unphotogenic. But? It's more uncouth to untag yourself from a photo (so vain) than to tag someone in a photo where they look terrible, because, well, "we just want to record the great times we had together, right?" Sinister.
SEND 'MAYBE' TO AN EVENT INVITE
Good for you. (Snub rating: 1 out of 5 pandering words of encouragement said with a perfect smile)
Someone's throwing a party, doing the legwork and burdening the risk of putting on an event. You know you don't have any plans for the night at the moment... but... uh... yeah, something better might come along. Because you're important like that. So throw 'em a bone with a 'Maybe.' Add a friendly line about prior (possibly fake) very cool engagements you already have going on, to let them know how valuable your time is -- under the guise being helpful and informative.
And don't show up.
A fine line. (Snub rating: 4 out of 5 hairs you totally didn't rip out of your own head)
The goal of a subliminal Tweet (or subliminal, passive aggressive Facebook status) should be to dig while simultaneously not losing your cool. If you're frustrated with someone and want to vent about them publicly behind their back, you must avoid appearing lower status by adding a little humor, or by insinuating that you're sane one in this matter. A subtweet is a tricky thing to maneuver, but one you must not let your emotions overwhelm. Otherwise, you look weak.
NOT RESPOND TO CHAT EVEN THOUGH YOU'RE CLEARLY LOGGED INTO GMAIL / FB
It's alright. Excusable (Snub rating: 2 out of 5 daily affirmations said to yourself in front of a mirror)
I don't know how the kids do it these days, but chatting via Gmail or Facebook is extremely hit or miss; while most people use both sites and spend a lot of time on them, only a few will use their native chat service. It can be confusing to configure chat on/off activation, whether others can see that you're online despite those choices, or if you somehow synced it to your mobile device, etc.. So, if you do get a message from someone via these platforms, feel free to get one over on them by ignoring it and apologizing that you missed it. This is completely okay.
ASK FOR DETAILS ON SOMETHING YOU ALREADY KNOW
Cuts deep. (Snub rating: 3.5 out of 5 patronizing inquiries on how things are going)
"What's your email again?" you ask, in your best sincere impression. You know their email along with their whole internet presence -- and they know you know, too -- but you're going to make them answer on your terms. "Where's the party again?" (It's clearly stated on the Facebook invite) This will drive them crazy.
UNFRIEND THEM ON FACEBOOK
Big statement. (Snub rating: 5 out of 5 fuck you's)
Probably the biggest statement you can make. It's certainly not subtle. It could actually be a sign of weakness to be the one pressing the unfriend button -- the equivalent of being the first to yell in a snide remark contest -- you lost your cool first. Obviously, if it's someone you met on your first day of college and never saw again, it's not a big deal. But if it's someone you see often in real life, this is a big statement. Don't unfriend them on Facebook unless you're fully prepared to unfriend them IRL