Spamming in Yahoo Messenger
Do u want to irritate your friends on yahoo messenger here is a way to do that. Just hold ctr+shift+r for some time. This is the shortcut for requesting contact details. Every time you ask for contact details a new window appears in the other persons computer a kind of flaw in yahoo messenger.
NOTE: This is a very old trick and it may not work on some versions of yahoo messenger. Try your luck, have fun