Do you wanna know who’s hiding from you? Do you want spy a buddy? Heres some tips:

1. See the main window of Yahoo! Messenger. An “offline” or “invisible” user will show a gray icon on the left of the username. Double-click on the username to open this window.

2. Click on “Voice” icon on the toolbar, or select “Contact” menu and select “Enable Voice Chat“

3. The deciding part… there are 2 possible result:

If the user is offline, you will get this message

4. But if the user is invisible (actually online), you will see the Voice Toolbar (marked red in the picture) like this:
Enjoy now check your friends if they are hiding… There lot of methods aside from this buti hope this will help..