One person says their slightly odd sideburns shouldn't matter, but the other person disagrees.
The words appear when the audience laughs.
もみあげって服装とか髪型とは違って明確な基準点ないじゃないですか
Unlike clothes or hairstyles, sideburns don't have a clear reference point, you know?
Textbookもみあげは服装や髪型とは違って、明確な基準点がありませんよね。「〜ないじゃないですか」 isn't a double negative: 「じゃないですか」 just asks for agreement, like textbook 「〜ですよね」 ('you know how…').