The reference is to a line about a “father’s brother’s nephews’ cousin’s former roommate”. Potentially you are your father’s brother’s nephew (or whatever combination of father/mother, brother/sister, nephew/niece that’s applicable to you, unless both your parents were only children), so you can go ahead and add that on to anything to make it sound more obscure.
“Oh that guy? That’s my father’s brother’s niece’s coworker” = that’s my coworker.
“My uncle’s brother-in-law’s daughter broke that” = I broke that.