unethnical

When people of a distinct race and culture break away from the customs and traditions that define their ancestry.

<Abuelo> Come on kids, let's get ready for the Cinco de Mayo parade.
<Pepito> Oh, Abuelo! We won free NASCAR tickets for the race today. Can we postpone it til tomorrow.
<Abuelo> NASCAR over Cinco de Mayo?! That's unethnical!

Unethnical

Describing something as being against a stereotype that has been attributed to your ethnicity, almost as if the stereotype in question was a true and vital part of your culture.

Jarquikas - "Hey man, wanna' go grab some fried chicken?"
Drontorius - "Nah nigga'. I don't even like chicken."
Flabquashio - "That ain't right! You is unethnical."

Brodrikus - "Hello sir. Would you care for some Kool-Aid?"
Dontiquo - "Man why you be talkin' all clean and shit? That's unethnical. But yeah nigga' I want some Kool-Aid."