The surname of Barry Kripke.
Season 6, Episode 14 - The Cooper/Kripke Inversion
Aired January 31, 2013
When Sheldon is forced to work with Barry Kripke, he is surprised to find his work is not at the same level as Barry's. Meanwhile, Howard and Raj spend $1,000 on action figures that of themselves, landing Howard in trouble with Bernadette.