I make a couple of prank apps, so I think about this more than most people probably should. A good prank is a small shared joke. For about thirty seconds someone believes something silly, then they find out, and both of you laugh. A bad prank is the same setup where only one person is laughing.
The difference is rarely the prank itself. It's who you play it on, what they believe during those thirty seconds, and how fast you tell them. So here are the rules I'd use, the hard lines I'd never cross, and some ideas that are actually fun.
The basic test
Before any prank, I ask one question: when I reveal it, will they laugh too?
Not "will they eventually forgive me." Not "will they laugh after they calm down." Will they laugh, more or less right away? If the honest answer is "probably not" or "it depends on their mood," skip it. There are plenty of other pranks.
A few things make that answer more likely to be yes.
Know your audience. Your friend who loves hacker movies and quotes them at dinner is a great target for a fake hacking screen. Your aunt who already worries her phone is being spied on is not. Same prank, very different result. Pick people who share your sense of humor and who you know well.
Reveal quickly. The longer the fake lasts, the more real it becomes in their head. Thirty seconds is a joke. Thirty minutes is a stressful afternoon. I think a minute is about the upper limit for most phone pranks. Have the reveal ready before you start.
Keep the stakes silly. The thing they believe should be absurd, not scary. "Your phone is now running a cat translation program" is silly. "Your bank account was just emptied" is panic.
Be there for the reveal. Pranks you send and then walk away from are how misunderstandings happen. Stay close, watch their face, and end it the moment it stops being funny.
Pranks that aren't worth it
Some pranks fail the test almost every time, no matter how well you know the person. I'd skip all of these.
- Fake emergencies. A fake message that someone is in hospital, had an accident, or died. These cause real fear, and that first rush of panic doesn't go away just because you say "kidding."
- Fake police or authorities. Messages pretending to be the police, immigration, the tax office. People have real anxiety about these, often for good reasons.
- Fake breakups or cheating "evidence." Relationships are not prank material. A fake text that looks like it's from someone's partner can do damage that outlasts the joke by a long way.
- Anything about money being lost or stolen. Panic about money is not fun for anyone.
And some people are just off limits for screen-based pranks:
- Elderly relatives who might genuinely panic, or who may not understand what an app can and can't do. A fake "hacked" screen can be truly scary for someone who already feels unsure with phones.
- Young kids who may not get that it's a joke, even after you explain.
- Coworkers, in a way that could get them in trouble. A fake message on a colleague's screen that their boss sees out of context is not funny for them. Workplaces have rules, and you don't want to be the reason someone has an awkward conversation with HR.
The hard line: when it stops being a prank
This is the part I care about most, so I'll be direct.
A fake message or fake screenshot shown to a friend for a laugh is a prank. The same fake used for any of these is something else:
- Shown as "evidence" to make someone believe something false, like proof that someone said something they didn't.
- Used to get money from someone, or to trick them into doing something they wouldn't otherwise do.
- Used to harass or scare someone, or to keep a "joke" going after they've asked you to stop.
- Made to impersonate a real person or a real business in a way that misleads other people. A fake text "from" a bank, a delivery company or a real named person that gets passed around as real.
Depending on where you live, those can fall under laws about fraud, harassment or defamation. The details vary a lot by country, and I'm not a lawyer, so I won't pretend to tell you exactly what applies to you. But the simple version holds pretty much everywhere: if a fake is meant to deceive someone in a way that hurts them, it's not a prank, and "it was just a joke" usually isn't a defense.
Also, one point on how these apps work. My prank apps only create things on your own screen. A fake text in the Fake SMS app doesn't send anything to anyone. A hacker screen doesn't hack anything. Nothing leaves your phone unless you take a screenshot and share it yourself, and once you do that, what happens to it is on you.
Some prank ideas that pass the test
Here are a few I think are genuinely good. They're short, silly, and easy to reveal.
The hacker screen for the movie fan. Your friend loves heist films. You hand them your phone, or prop it next to their laptop, running a dramatic hacker terminal with scrolling green text. Bonus points if the "hacked" reveal at the end is a photo of their own dog, or of them asleep on the couch. They'll know within seconds it's fake, and that's the point. The fun is the theater of it. Hacker Screen has a bunch of scenarios like a security camera feed or WiFi "breach," matrix rain, and lets you pick a gallery photo or video as the final reveal. It doesn't hack anything. It's an animation.
The absurd text from a mutual friend. Make a fake text on your own phone that looks like it's from someone you both know, saying something ridiculous but harmless. "I have decided to only communicate through interpretive dance from now on." "Is it normal for a pigeon to follow you home three days in a row?" Show it to your friend, let them read it, wait for the confused look, then show them it's fake. The whole thing should be over in under a minute. I'd only do this with a mutual friend who'd find it funny too, and I'd tell them afterward. Fake SMS does this; the message just sits in a fake inbox on your phone.
The very slow "update." Set your friend's screen saver or wallpaper to a fake "Updating, do not turn off, 1%" image while they're away. Harmless, mildly confusing, easy to undo. I like this one because it doesn't even need an app.
The reverse prank. Tell a friend you're about to prank them with a fake hacker app, then don't. Just wait. The anticipation is funnier than most actual pranks.
If it goes wrong anyway
Sometimes you misjudge it. You thought they'd laugh, and instead they look genuinely upset. When that happens, stop immediately. Show them it's fake, say sorry properly, and don't try to rescue the joke with "come on, it was funny." It wasn't, for them, and that's the only vote that counts.
The best pranksters I know apologize fast and don't sulk about it. They also tend to get to keep their friends.
If you like these kinds of things but want to understand the more serious side of fake content, I wrote about spotting AI-generated images, which is basically the same question pointed the other way: how to tell when someone is trying to fool you.