Season 5: Episode 21 - The Hawking Excitation

The Hawking Excitation: When Stephen Hawking comes to lecture at the university for a week, Wolowitz is given the enviable task of maintaining his wheelchair. Sheldon begs Wolowitz to introduce him to Hawking, but Wolowitz only agrees after making Sheldon do a few humiliating tasks, including doing his laundry, cleaning his room, and taking his mother dress shopping.