Wil Wheaton returns to The Big Bang Theory on the episode "The 21-Second Excitation." He once again causes problems for the fellas.
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The Big Bang Theory Season 4 Episode 8 Quotes

I'm guessing 21 seconds had something to do with that, too.

Wolowitz

I find zombies dancing in choreographed synchronicity implausible. And also it's really scary.

Sheldon