I walked in on my little sister when she was naked.
The thing I have to say is that my little sister is a big sister with big tits & ass with juicy lips upstairs & downstairs. I say whoever is going to be my brother-in-law is going to be a very happy person.
Listen here, buddy. You think it's funny to objectify your own sister? Okay, maybe it is a little. The joke is about the narrator walking in on their sister naked and then commenting on how attractive she is and how lucky her future husband will be. The humor comes from the unexpected and slightly inappropriate nature of the observation.
