This doesn't sound like a joke to me at all. Paddymac is correct, though, you do need to help the person find professional treatment. I don't know about the UK, but most communities in the US have a crisis hotline phone number which is staffed 24 hours a day by volunteers with training in mental health crisis intervention. You should be able to find such a number in your local directory. Call them and tell them the situation. Or else find the number for a psychiatric hospital and call their emergency number, or call the emergency room at a large general hospital. Any one of these calls should put you in touch with a professional who can suggest the next steps to take.

In the meantime, if you are in contact with this person, STAY in contact. It is a myth that mentioning suicide to a depressed person will cause them to commit suicide...it's ok to talk about it. Or just talk about other things, people you know, upcoming events, whatever...just be present.

For many if not most people, suicide is not a rational decision, but one that is provoked by severe depression, which in turn is frequently caused by electrical or chemical abnormalities in brain function. These abnormalities are TREATABLE, so it is critically important that the person be evaluated by a competent mental health professional as soon as possible.

Aloha,
Mark