Mayim Bialik, Jim Parsons Mayim Bialik, Jim Parsons

Hewlett and Packard. Lady and Tramp. What do they have in common?

They're both couples costumes Sheldon (Jim Parsons) and Amy (Mayim Bialik) each want to dress as for Halloween on Thursday's The Big Bang Theory (8/7c, CBS) — except neither likes the other one.

Big Bang Theory's Simon Helberg: Wolowitz gets "planet shock" when he returns from space