Season 4: Episode 15 - The Benefactor Factor

The Benefactor Factor : An incredibly wealthy older woman is considering making a huge donation to the school's science program.  When she takes a liking to Leonard, Sheldon attempts to pimp Leonard out in the name of science. Jessica Walter guest stars as the older woman that wants Leonard. Josh Molina guest stars as the president of the University. Leonard swears that he will not sleep with her just for the money. But in the end he succumbs to her seduction.