Someone who works for AQA for example. They're disgusted by a wrong answer so they get in touch with the person on Facebook when they get home.
Sitting there marking an A-level biology question about diabetes and the student's started going on about the respiration system or something unrelated to diabetes. Does a big red X at the bottom of the page, pressing the pen down so hard that it nearly rips through onto the desk below cos he's so pissed off. Flips the paper over to look at the front and copies their name into his phone.
Gets home at 5pm, runs to his laptop, logs into Facebook, searches for 'Peter Whitaker' and clicks on the most likely result. Sends him a message:
"Why did you write that answer on the diabetes question??? Completely wrong wtf??? WHYYY did you start talking about the respiratory system you obviously didn't learn anything in college? You thick twat what is wrong with you? You did shit in the exam didn't even get 50% haha you're fucking thick hope you don't get into uni now cos you don't deserve to, I marked some of your questions wrong even though they were right as well ha ha. Idiot.
PS: you look like a cunt in your profile pic.
PPS: Fuck off and die."