Jonathan Treadgold's comment was related to a jury after he denied murder at a house in Gladstone Street, Mansfield.
The youth who died was Liam Gray, 18, a father-of-one and also known as Liam Peters. Treadgold, of Kent Close, Worksop was 17 at the time of the death on August 1 last year.
Nottingham Crown Court heard that Treadgold, who is now 18, gave a blood sample seven hours after the incident. This gave a reading of just over the legal limit for a driver.
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But Dr Stephen Morley, who analysed the sample, said that would indicated that Treadgold would have been "about three times the limit" at the time of Mr Gray's death.
The jury heard a recording of the 999 call from the house as efforts began to try and help Mr Gray, who planned to move to Birmingham the next day.
The jury was also shown a police officer's film of the arrest of Jonathan Treadgold. As he was being led to a police van, he can be heard saying: "See you in 15 years."
An officer tells Treadgold that he is being arrested under suspicion of causing GBH. When he asked Treadgold if he understands, he replies in tears "yeah."
On the opening day of the trial, the court heard that the pair and another friend Reece Lambert were known as "the three stooges."
On the morning of the death, they walked to a Costcutter shop, returning with two bottles of red wine, a couple of cans of beer and some lemonade.
James House QC, prosecuting, said: "The three youths were considered good mates."
Treadgold later suggested that he had been bullied.
But Mr House told the jury: "He is well aware he is responsible for the killing of Liam Gray. He is casting around for a defence."
Pathologist Dr Stuart Hamilton said that "moderate force" would have been used to inflict the injury, which left "blood escaping from the heart into the chest cavity."
The trial continues