The Einstein Approximation
The Big Bang Theory Season 3 Episode 14 (02/01/10)
When Sheldon gets stuck on a problem he's trying to solve, he snaps. Sheldon decides that like Einstein, he needs a pedestrian job to keep him distracted so he can solve his problem. Sheldon tries to apply for a job, but after failing he shows up at the Cheesecake factory and just begins working for no pay. After busing and eventually waiting tables, dropping some dishes help him solve his problem and he takes off.
Meanwhile, when Raj suggests they guys go for some roller skating and disco dancing, Leonard and Wolowitz take the idea and go on a double date, embarassing the ladies in the process.