A 16-year-old boy has been detained for killing a former best friend after the pair traded insults on Facebook.
Salum Kombo, 18, was stabbed in the chest in Bromley-by-Bow, east London, in December after calling his killer, then 15, names including "pussy".
The trial heard the boy, who was found guilty of murder at the Old Bailey in May, could not take the "loss of face".
The teenager, who cannot be named, has been ordered to serve a minimum of 14 years.
'Act of cowardice'
Sentencing the boy at Southwark Crown Court, Judge Nicholas Loraine-Smith said: "There was nothing brave about what you did.
"This was quite simply an act of cowardice, as so many stabbings are."
David Jeremy, prosecuting, said a previous friendship between Mr Kombo and the defendant had turned to "hostility" and the pair had a fight last summer after a football match.
The court heard that on the night of the murder, the killer had been with friends outside a fish bar.
The trial heard how they tried to calm him down when he became angry and started talking about stabbing Mr Kombo.
When Mr Kombo turned up, he and his killer walked off, apparently to settle their differences.
However, the younger boy then pulled out a knife without warning and stabbed Mr Kombo in the upper chest.
The trial had heard the boy had tried to fight Mr Kombo before but had been restrained by friends and had his knife taken away from him.
However, Mr Kombo had later returned the knife, which later killed him, to the defendant.
After stabbing Mr Kombo, the defendant was seen "pounding" a wall and "howling at the perceived affront to his own dignity, being called a pussy", the court was told.
"That was the pathetic reason as to why this terrible event happened - because he wanted to show he wasn't a pussy," said Mr Jeremy.
The boy later admitted the stabbing but claimed he had been acting in self-defence.
Graham Trembath QC, representing the defendant, said the two boys had been best friends and "like brothers" and believed he was acting in self-defence by striking a pre-emptive blow before a fight which he thought he was going to lose.
An Old Bailey jury rejected his explanation and convicted him of murder in May.