Ok kids, here's the deal.  Telling someone "I can't believe/don't understand why you're single" is *not* a compliment.  It may *sound* almost like one, and undoubtedly the person saying it means it as one...but it's not.  It just reminds the person you're saying it to that they are, in fact, single.  it dredges up memories of why their last relationship(s) didn't work out, reminds them that their ex is currently in a long term 
relationship and they're still alone, makes them wonder again why the 
last (two) people they dated suddenly just stopped calling/answering 
their messages with no explanation, makes them count in their head how 
many months it's been since they were even asked on a date, and somehow 
makes them feel like they *should* be in a relationship and there must 
be something wrong with them because they're not. 
Better compliments 
include "Hey!  You look awesome!", "Your show is really funny and your 
character is hilarious" (only works if they have a show), "You're a 
super cool person!  Let's go get ice cream -- I'll pay since cool people
 shouldn't have to pay for their own ice cream.", "You've got the moves 
like Jagger", "If I ever get stuck in a dark alley with you, I know I'll
 be safe because your guns are HUGE", and "Your outfit is gangsta". 
