It's pretty fast to do. The above suggestions are good too. Of course, everything in 3D is fake and the real goal is to make people "think" things that aren't true. :D The easiest way is to add a color to the TV screen's glow channel, turn on Indirect Lighting and bump up the strength to 500%. In my fast little scene above, I also changed the Ambient light to Sky since it is preset for a natural blue-ish cast.

I then added a blue spot (45 degree spread) slightly above the TV, pointing at the chairs with soft shadows turned on and a 100% falloff setting.

This scene was built PDQ with the stock objects that come with Carrara.