A "wild animal" teenager filmed himself repeatedly stamping on an unconscious man's head before sharing the video on social media.
Callum Page, from Dover, screamed: "I want you to remember this when you wake up" as he rained at least five powerful blows on Jake McDonald, laying defenceless in a pool of blood.
The 18-year-old then shared the 38-second clip on Snapchat gloating about the trauma he had caused Mr McDonald in the unprovoked attack.
A judge called the video, which was reported to police, "unforgettable" after the court heard Mr McDonald’s ear had been severed in the assault.
Page, of Cleveland Close, is now serving five years and four months in a Young Offenders' Institution.
He pleaded guilty to causing grievous bodily harm with intent at a previous court hearing.
Canterbury Crown Court heard the attack began near St Mary's Church in Cannon Street, Dover, in the early hours of November 9 last year.
The pair had been drinking with different groups of friends.
Page was Face-Timing his then girlfriend when Mr McDonald asked him for a cigarette.
She heard Page attacking Mr McDonald as he screamed to be left alone, the screen then went black before the defendant could be seen covered in blood, the court heard.
Page’s friend pulled him off unconscious Mr McDonald, who was laying motionless throughout the assault.
The court heard the same friend later spotted Page laughing at a video on his phone - as he walked away a notification appeared on his own mobile.
Bragging, Page had shared the video on social media networking site Snapchat with the words: “Man tries to violate me.”
Prosecutor Vivian Walters explained Page claimed self-defence in his first police interview, where his phone was seized.
But when police presented the video in his second interview Page gave “no comment” answers, adding the footage made him uncomfortable.
Meanwhile Mr McDonald’s ear which was partially severed had to be sewn back on, his teeth also needed ongoing re-arrangement.
Keen sportsman Mr McDonald told the court he was unable to eat solid food for eight weeks, had to move back to his mother’s and couldn’t work for five weeks.
Page remained passive in the dock and didn’t appear to look up when footage of his gratuitous violence was played.
"You behaved like a wild animal. You were punching, kicking and stamping on a man who was defenceless..."
Judge Mark Weekes told him: “You behaved like a wild animal. You were punching, kicking and stamping on a man who was defenceless.
“The video produced that has been shown to the court, few who have seen it will forget the sight of the gratuitous violence on a man who was in very serious distress in a medical sense.”
Mitigating, Emin Kandola, explained her client was immature, remorseful and "deeply ashamed".
“He can’t explain what came over him, he was intoxicated, he does not remember posting a video.
“To this day, Mr Page feels sick to his stomach, he is still disgusted by his actions.”
In a letter to his victim read in court Page said: “I would like you to know I’m truly sorry for my actions - it is one of my biggest regrets.”
After the hearing Det Insp Nigel Douglas, of Kent Police's Criminal Investigation Department, said: 'This was a horrific attack which the victim was lucky to survive.
"The strong case we put together gave Page no alternative but to plead guilty and I am pleased this violent offender will be off the streets for a significant period of time."