first off, best icon ever! (or, um, perhaps more accurately, I've always gotten a kick out of that quote).

And I concur! Bickering (flirting?) like that as friends speaks to their physical chemistry (though I must admit I've always seen more chemistry between Sheldon and Penny, then Leonard and Penny).

Finally, I'm looking forward to the gray area! It's fun to see how people play with ideas.