I would wager that if there was no Penny in that show they would not attract the millions of viewers they have now.
I don't hate you. I love you silly. Like... A little brother... Except not related at all... And not classified as part of the same family... I love you like a friend. I actually mess with my friends aloooot. The guys flip or make jokes. The girls take it too seriously. So much fun how they react.
I treat my friends the same way I treat you. That's the short version. I love you like one of mi amigos.