* Send a message saying "I have {insert random STI}, best get yourself checked out..." to a random contact in your phone.

* Send "So, I've been thinking... How about we try friends with benefits?" To a random contact.

* If you have anyone in your phone as Boss, Manager etc, send them an email with a template of a fairly harsh notice of resignation.

* If it's a woman, send to Mum / Mom / Dad "Hey, I'm going to be a mother! No idea who the father is but it's exciting!".

* If it's a man, send to Mum / Mom / Dad "Hey, so I drunkenly hooked up with some stranger from a bar and I've knocked her up... What to do?"

* Select 2 random contacts A & B. Send to A something about how B won't shut up about wanting to sleep with A.

* Select 2 random contacts A & B. Swap their details (phone no, email etc)

* Respond 'no' to all upcoming calendar events

* Post your last password reset link from your email to Twitter

* Text your reddit username to whatever contact you text the most (likely your significant other)

* Silently remove the most popular, by email count, person from your VIP email list (likely your boss)

* Add entries to the auto correct list: :) -> ;) hey -> heyyyy

* Change any daily alarm from AM to PM, but leave the alarm enabled

> * Silently remove the most popular, by email count, person from your VIP email list (likely your boss)

Or block that person and add an auto-reply with something insulting.

Copy the browser history from a random day into an email and send to X random contact.

Factory reset your phone (idk if it can do this, but I want this one)

Update all the contact names in your phone with names of adult film stars.

If this is still an issue, send a unicode string that will reboot an iPhone to a contact.

Send a random Bible passage to a contact, or tweet it, or Instagram it.

Ditto, but random Quran passage.

Post an Inspirobot image to Instagram/twitter. (http://inspirobot.me/)

Dial a random (but valid) US phone number.

>Send a random Bible passage to a contact, or tweet it, or Instagram it.

>Ditto, but random Quran passage.

Trivia: Half of Quran verses consists of corrupted Biblical passages (due to the fact Syriac Aramaic text interpreted as Arabic), along with other half of weird poetic legal texts.

Set an alarm to a random time in one of the upcoming nights. Sound is one of the top 10 tracks in a random country.

* Tweet a death threat to a random stranger

* Encrypt a random photo and email to the NSA

* Repeatedly admit to random horrible crime types on Twitter.

Am I doing it right? You did say life-ruining.

All of these suggestions are noted and appreciated

* Change all contact names to "Mom" or the most frequently contacted individual.

Frequent, random Internet searches regarding bioweapons, chemical weapons, fabricating nuclear weapons, and how to get in contact with various terrorist organizations.

* Subscribe to a random podcast

* Delete a random app

* Attempt to Rick Roll a contact

* Send the last thing you asked Siri to twitter

* Random photo to facebook

* Name all contacts in the phone the same

Borjes' Lottery in Babylon explores that concept further https://en.wikipedia.org/wiki/The_Lottery_in_Babylon

Send "heyyyy" to 20 random contacts.

Individually or group chat?

Create a group chat with all contacts containing 'ex' in the name/comment. Send 'sup losers' to the chat, leave the chat.

If only "leave the chat" were a real iPhone feature...

It is with iMessages. Not sure if you can leave one you've started, but I've left some that others have started (my email address was similar to their friend's).