The Einstein Approximation (2010)

Sheldon's search for the answer to a physics problem keeps him up all night for several days and he becomes obsessed with finding the answer. One attempt in a mall ball pit has Leonard jump in and try to get Sheldon out as he pops in and out, shouting "Bazinga!". He then decides that he needs a menial job to think better because Albert Einstein came up with the Theory of Relativity while working a menial job at the Swiss patent office. Since the United States Patent and Trademark Office is near Washington DC, and he doesn't want to move out of Pasadena, he interviews for any menial job with the County of Los Angeles, where he is interviewed by a woman played by Yeardley Smith. Since he is tossed out, the next menial job he can think of is to work at the Cheesecake Factory with Penny. He shows up and works as a busboy and waiter, but never is actually hired, although as he does not want pay, the restaurant appears happy to let him continue, and he turns out to be a much more efficient waiter than Penny. After dropping and breaking a tray of dishes, the scattering of the shattered pieces leads him to the answer to his problem, and he promptly walks out without cleaning up the mess.

Meanwhile Leonard, Penny, Howard, and Bernadette go to disco night at the roller skating rink. The men embarrass the women with their outfits and dancing.

Recurring characters: Melissa Rauch as Bernadette Rostenkowski

Title reference: Sheldon's attempt at solving his problem by working in a menial job, comparing it to Albert Einstein's discoveries made while working in Switzerland in the Patent Office.