Practical Joke anyone can do on the Internet

ORIGINAL SMILESPEDIA WORK FOLLOWS

WARNING: Do not do this on people that might take legal action against you.

You have a friend that you want to annoy? Are you familiar with the system that allows people to comment on websites?

Most of them have an option called “Subscribe to comments”. If you comment on a topic, they will email you every time someone posts a comment on that topic.

Now, find some very popular topics that you know it will annoy your friend. (DO NOT DO IT TO YOUR ENEMIES).

Remember to add your friend to several such topics, just to make sure.

And tell him who did to him, perhaps when other people/common friends are around.