I found this on the net........Flirting is, in my experience, something of a lost art, especially amongst nerds. They simply don’t understand how to flirt. Too many young nerds have hit some sort of mystical, magical combination of bad influences that seems to have convinced them to make all the wrong moves. It seems to be split into the camp that believes that to get the girl you have to either be intensely sincere to the point of being creepy and the camp that is so nice and obliging that they may as well tattoo “WELCOME” on their backs and resign themselves to a career of women wiping their shoes on them.
But hey. You want to learn how to flirt and clearly many people have gotten the wrong impressions so let’s start off with what it’s not:
Flirting isn’t complicated.
Flirting isn’t a wide variety of subtle signals you have to keep an eagle-eye out for.
Flirting isn’t intense.
Flirting isn’t making fun of people, “negging” or generally being an azzhole.
So let’s move on to what it is and how to flirt.
Flirting is, at it’s core, a way to engage, size up and generate attraction in a perspective mate. It’s light and it’s friendly. It’s a combination of banter, body language and teasing.
Let’s break it down. Flirting really comes down to a three key points:
Teasing
Teasing, put simply, is the art of saying something mean that really means “I like you”. Flirting is essentially teasing with intent. It’s banter; a playful back-and-forth between two people. It’s fun and inclusive and a little silly, and when done right, it’s incredibly attractive.
There’s a certain structure to teasing as flirting; in another context it could look like a couple verbally jousting for social dominance. The keys are tone of voice and to be careful not to make the teasing too harsh. An easy short-hand to teasing is to imagine the other person as your bratty little sister; you’re needling at them for a reaction rather than trying to actually insult them. As you’re teasing, you can incorporate a number of ideas. You can start a role-play, establishing some sort of ridiculous fantasy situation; if she talks about a love of cooking or food, you can say “Hey, you can totally be my personal chef. I’m going to have you make all these insanely elaborate meals for me.” If she’s clumsy or drops something, “Wow, you’re officially the worst personal assistant I’ve ever had. It’s bad enough you wear these inappropriate outfits around the office, but this is the final straw.” “That’s it. We’re totally breaking up. Give me back my CDs and I’m keeping the dog.” Think of it like an improv exercise, especially if she teases you in this manner; the response is should be”Yes, and…”, extending the scenario.
Challenging is also an important part of teasing and flirting. Too many nerds have Chronic Nice Guy syndrome, and won’t stand up for themselves when a woman gives them ****; a teasing challenge is a playful indicator of some spine as well as bait into being more aggressive. Challenges work on the same part of the contrarian part of human psychology; by telling someone they can’t have, be or do something, the first impuse is “Yeah, I totally can”. You can challenge in any number of ways; you can call her a name: “Dork”, “Princess”, “Brat”, “Crazy”. Challenges can be a miniature cold-read, giving them an opening to open up about themselves: “I bet you must drive your parents crazy.” “You can’t be from around here; you must be a West Coast girl. I can always tell.” It can be physical: “OK, obviously we’re going to need to settle this in the manner of our ancestors: thumb-wrestling. And I should warn you, I’m totally the thumb-wrestling champion of the Eastern seaboard.” It can have a certain sexual edge to it to raise the heat:”Your last boyfriend just didn’t spank you enough, huh?” “Don’t make me come down there little girl, I’d eat you for breakfast”.
A rule of thumb is that if she’s not laughing, agreeing with you, playing along or playfully disagreeing, then you’re doing something wrong. Dial it back a notch until you figure out what you did wrong, then calibrate accordingly.

I saw this question,and I got into a conversation about it with someone privately. Here's what I could say. There's a way of flirting that is good,it shows that you have an interest or enjoy speaking to a person, that you want to show a person that you enjoy their company. There's also a way of flirting that can be harmful if not done for the right reasons. Some people use flirting as a way to make someone jealous. There are also people who take flirting way too far. Teasing can be the same, there's harmless teasing,as in just joking or having fun with a friend or partner. There's also teasing that can be hurtful. Teasing can be one step beyond flirting,so I'm told, that it can be much more hurtful then flirting.

It's never ok to play with a person's feelings or emotions though, by flirting or teasing them.

What is flirting? What is teasing? Is it fairgame to 'play' with peoples emotions and tease them?

I agree, there must be an underlying need to seek attention or maybe have a type of power over the opposite sex? I think light flirting is fun, but hard out in your face is just a turn off.

I hate PC...

PC hates you too, big boy, lol. JK

What is flirting? What is teasing? Is it fairgame to 'play' with peoples emotions and tease them?

If you want to flirt, keep eye contact for 4 seconds then look away. If you want assert authority keep eye contact for more than 4 seconds.