I was Spock!
Season 3 Episode 01 – The Electric Can Opener Fluctuation
Love this one!
Season 7 Episode 17 - The Friendship Turbulence
Season 2 Episode 02 – The Codpiece Topology
Penny: Oh, gee, well, thankyou for that. But, um, I think for now Leonard and I are just going to stay friends.
Sheldon: No, that response is unacceptable to me.
The worse nightmare of Sheldon Cooper!