TV 'Big Bang Theory' Stars Revel in Huge Ratings Published 8:43 PM PST, February 7, 2013 With an average of 18 million viewers tuning in every Thursday night, The Big Bang Theory has become ratings gold for CBS. Despite six years of continued success, the cast of TV's #1 comedy tell ET they're still trying to wrap their heads around the extreme popularity of their show.Pics: Star Sightings!"When we hit 10 million a couple of years ago, Kaley [Cuoco] hunted me down at the gym to tell me," remembers Johnny Galecki with glee. "I was so excited. We thought that was the end-all, be-all."What's the sitcom's secret? Star Jim Parsons has a theory."[Syndication] exposed us multiple times a day on a couple of different networks," speculates Parsons. "[It] will make you love us."Related: Kunal Nayyar Goes 'Beyond' The 'Bang'Of course, it doesn't hurt that co-star Simon Helberg is Big Bang's personal cheerleader in his free time."I hand out flyers over the weekend," Helberg jokes. "I dress up as Spider-Man…with the spinning sign."Watch the video above for more from The Big Bang Theory's stars!