When you find out you're significant other no longer wants to be with you, after seeing that his/her status on the oh so famous myspace now claims to be 'single', as opposed to 'in a relationship'. Other big clues are when you're removed from their top 8, or they have proceeded to flirt with others in their 'comment' box. God bless Myspace.
'Did you see that Tyra's myspace says 'single' ?'
'haha, yeah, Brain was well myspace dumped' ...