Other partygoers chanted “light it, light it, see what it does” as the oil was poured over Steven Simpson and a reveller held up a cigarette lighter.
Sheffield Crown Court heard that Jordan Sheard, 20, flicked the lighter and Steven went up in flames with Sheard and others running away instead of helping him.
The teenager, who suffered from Asperger’s syndrome, a speech impairment and epilepsy, died in hospital from 60 per cent burns the next day.
Sheard, who initially tried to blame Steven for setting himself on fire, eventually admitted manslaughter, and was jailed for three-and-a-half years.
Judge Roger Keen told him: “What it did was engulf him in a fire. You tried to briefly assist and then you ran away. That in my judgment is serious aggravation.”
The court heard the only person who went to Steven’s aid was neighbour Sean Banner who burned himself in the process. But when Mr Banner returned to the flat in Pleasant View, Cudworth, near Barnsley, he was initially arrested on suspicion of murder.
Sarah Wright, prosecuting, said that earlier in the evening Sheard, who vaguely knew Steven, and two others joined the party and were let in despite having not been invited.
Steven was openly gay and had moved to the flat where he lived alone because of bullying at his previous address.
His father Kevin was with him at the hospital before he died and he told him what happened.
“A lad took a bottle out of a drawer and chucked it over him,” he said. “The next thing he remembered was going up in flames. One of the other lads took a lighter out of his jacket, lit it and he went up in flames.”
Ms Wright said despite his learning difficulties Steven was sociable and had lots of friends.
The teenager’s learning mentor at Barnsley College said: “He was a brilliant representative of Barnsley College and a pleasure to teach and was very popular.”
At first nobody had turned up for Steven’s party on Friday, June 22, last year where a neighbour had made a buffet and provided beer.
Steven then went to collect partygoers and a number of young people arrived. He seemed to be enjoying himself and there was horseplay and Steven was encouraged to strip to his boxer shorts.
Partygoer Matthew Clark said Sheard “took the mickey” out of Steven over his sexuality and drew on his belly as Steven got more drunk.
Some time after 2am partygoer Reece Thompson poured Calypso tanning oil over Steven in his bedroom and Ms Wright said: “Steven did not object, he seemed to be enjoying the situation.
“Then Jordan Sheard took out a cigarette lighter struck it and held it to Steven and he went up in flames.”
Sheard told police he had been egged on by others and held the lighter to Steven although he would not have done it had he been sober.
Andrew Smith, defending, Sheard, of Darfield Road, Cudworth, said: “It was the result of a criminally stupid prank that went wrong in a bad way. He is a pleasant young man with no edge to his character, hard-working and has a degree of intelligence. He has been deeply and significantly affected by what he has done and the tragic consequences that ensued.”