Just the tongue-in-cheek emoticon says it all. You can say whatever you want...almost whatever you want, anyway, and get away with it by using an emoticon. Something like "I didn't mean that...just joking, really" when you may or may not have been. That's the beauty of chat.
On a deeper level, what is it that makes it easy to chat up someone on 'chat'? Is it the knowledge that you can say anything and the other person won't see through you? Is this what allows you to mask your true emotions and feelings? Or sometimes, the other way around?
Either way, the person on the receiving end may never truly get the intended meaning. Or maybe they will but don't let on...they're probably using a complementary emoticon as well. An emoticon face-off, if you will.
Which emoticon will blink first?