Leonard Hofstadter:  I do have to ask you one favor .
Penny: Sure .
Leonard Hofstadter: Sheldon 's nervous about me leaving ; just keep an eye on him while I 'm gone .
Penny: Mm , I do n't know . Remember what happened when I took care of your goldfish ?
Leonard Hofstadter: Well , flush Sheldon down the toilet and get me a new _ one _ .