The Big Bang Theory Season 3 Episode 2 : The Jiminy Conjecture
Sheldon and Howard stake their most valuable comic books (Sheldon's "Flash of Two Worlds" against Howard's Fantastic Four #48) on a bet to determine the species of a cricket. Sheldon hears the chirps and says it is a snowy tree cricket and Howard insists it is a common field cricket. Along with Raj, the three spend a long time locating the cricket. They settle the bet by taking "Toby" to Caltech's depressed entomologist, played by Lewis Black. Howard is correct that it is a common field cricket, so Sheldon has to give up his copy of The Flash.