What does "gas" mean?
I'm currently watching Criminal Minds and there's a scene where one guy (Derek Morgan) holds a colleagues (JJ's) baby and says "Look, look, what's he doing? He's smiling at Derek Morgan." His colleagues Garcia and Prentiss glance at each other and say "Gas!" Then JJ looks at their boss Hotchner (who rarely ever smiles) and says "You're smiling!" To which he responds: "Gas!"
I found following explanations for the word "gas":
something/someone is a gas: used for saying that someone/something makes you laugh a lot
gas: fun; empty talk; something that gives pleasure
So, what does "gas" mean here in this context? Something like "you wish!" , "yeah, right..." or "haha"?
Ok, after writing this post I checked how they translated this into German. The dubbed version says "Na, klar." and the subtitles say "Quatsch". Both can be translated as "Yeah, right...".
Do you use "gas" in the meaning of "yeah, right". Is it common?