Receiving and forwarding on jokes by e-mail
It's not quite that the jokes themselves in the e-mails are dangerous to forward on but more that the e-mail that contains the joke is dangerous to forward on and this is simply because the e-mail has been around too many people.
In a very coarse way we could perhaps compare the situation to a person who has slept around too much in that his or her chances of contracting some sort of nasty ailment, syndrome or disease are much more likely than the person who maintains a conservative life style!!
Touching hands is a form of spreading germs and the more hands you touch the more likely you are to touch the hand of someone that has an infection. It is better to only touch the hands of people that you know and on a forwarded e-mail with a joke in it, there are a whole load of e-mail addresses there that you know nothing about.
Despite most computers having ant-virus programmes installed such as Norton, Kapersky etc, these programmes are not infallible and the odd worm or virus can creep in through the back door, put in the words of the computer technicians themselves.
And if you follow the journey of an e-mail containing a joke that is forwarded on from one person to another, you will see how it has already visited a whole load of e-mail addresses before it even arrives to you and then you send it off to another load of e-mail addresses. What is happening here? Well if you are lucky, nothing, but if it's not your lucky day the following could happen.
The e-mail with the joke is sent to ten e-mails who are presumably friends of the first person that sends the joke out. The original sender's computer is working fine but he hasn't spoken to one of his friends on the list for quite some time and it just so happens that the computer of this friend has a virus.
The e-mail arrives to this friend's inbox with the joke, and just before the e-mail is forwarded on to another ten e-mails the virus jumps on board. And there you have it. From now on, who ever opens up this joke is going to be infected by the virus or trojan and it will carry on as a deadly chain reaction. And for what? For the sake of reading a joke!
It is really far better to set up your e-mail box so as to send all these kinds of e-mails straight to the SPAM folder or the TRASH folder. If your friend has a good joke, let him or her tell you it over the phone or in person because it really isn't worth so much havoc and technicians' bills in order to liberate your computer of a virus just for the sake of a joke.