If this is a parallel to Family Guy, then I guess he had an affair with Karin.
N: Sasuke, you're having an affair? Ewww. S: No,no. This is my sister. N: Ewww. S: No, no, no. I mean she's my snake parter. N: Ewww. S: I mean I looked at her while she bit me. N: Ewww. S: I mean she's a whore. N: Ewww. (goes into mouth)