Definition: In this task, you will use your knowledge about language (and common sense) to determine what element the marked number refers to. The numbers are marked with two underlines around them, like: _ number _. Your answer should be chosen from the given text, and should not contain other words.
Input: 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 _ .

Sheldon