Leonard Hofstadter:  Let me ask you something : do you think it 's okay for Penny to have an ex - boyfriend sleep on her couch ?
Howard Wolowitz: No , I mean she 's obviously way out of line ...
Leonard Hofstadter: Thank you .
Howard Wolowitz: But if she dumps you , she 'll have a new boyfriend by tomorrow morning , and you 'll have a new girlfriend when you figure out how to build _ one _ .