[s2e20] The Hofstadter Isotope -

David Goetsch, Richard Rosenstock, and Steven Molaro.

is the 20th episode of the second season of The Big Bang Theory , which originally aired on April 13, 2009. This episode is a fan favorite because it introduces Stuart Bloom and marks a major shift in Leonard’s pursuit of Penny. Episode Plot Summary [S2E20] The Hofstadter Isotope

One of the most discussed moments among fans is Penny's invitation for "coffee," which Stuart famously takes literally, much to Penny's amusement. David Goetsch, Richard Rosenstock, and Steven Molaro

In an attempt to move on, Leonard convinces Howard and Raj to take him to a "normal" bar to pick up women. The excursion is a disaster; Leonard feels out of place, and Raj finds success only after becoming incredibly drunk. Key Character Moments which originally aired on April 13