Malcolm Myatt is now in a permanent state of happiness, after suffering a stroke that left him unable to feel sadness.
The stroke destroyed the area of Malcolm Myatt's brain that deals with emotion control and now he has no control over the fits of laughter that he has for no apparent reason, Metro.co.uk reported.
Myatt, from Cannock, Staffordshire, said that he has always been a happy person and loved telling jokes, but now he doesn't ever feel sad.
He asserted that he remembered what it felt like to be sad, but he would rather be happy all the time than the other way round.
Myatt's family insisted that his impulsive laughter is now contagious but it has left them on tenterhooks at sombre events such as funerals, wondering whether he may inadvertently lighten the mood.
Myatt, 63, was struck with the stroke in 2004.