In one photo, the pair is holding a trophy, their prize for "best couples costume" at a Halloween party. While their friends may have thought the look was awesome, Instagram users were quick to call out Sweetin for the offensive makeup "Thanks for wearing my culture as a costume. Really appreciate it," one person commented on Instagram. Another user wrote, "That is NOT a Halloween costume. It's the way my people celebrate the lives of those who have passed on. Please stop appropriating a tradition you don't fully practice or embrace."If you're not sure why this is a big deal, it's because Day of the Dead (or Día de los Muertos) is a Mexican celebration intended to honor deceased relatives . From October 28 through November 2, families remember family members who died in accidents, children who died in birth, and other relatives who died tragically. Families set up shrines for their deceased loved ones decorated with religious artifacts and yes, calaveras.Perhaps the most recognizable element of Día de los Muertos is La Catrina, the elegant skull that is symbolic during Day of the Dead commemorations. According to Andrew Chesnut , a Virginia Commonwealth University professor of religious studies who specializes in Latin America, La Catrina was created originally "as a satirical figure to mock the Eurocentric Mexican elite, whose policies were resulting in hunger and starvation for 90% of the Mexican populace." He told Refinery29 that "the skeleton is the representation of the death of the policies this dictatorship was having in Mexico." Clearly, there is a much deeper meaning to Día de los Muertos than pretty face makeup.It's a sacred family holiday, so when people try to sexualize La Catrina, it's offensive . And it's not Mexican Halloween. So when people wear face paint to look like calaveras or don ethnic costumes to mimic the culture, they're not honoring the holiday. Instead, they're using someone's culture as a costume. And as we've written before: that's just wrong.