Editor's note: Ruben Navarrette Jr. is a CNN.com contributor and a nationally syndicated columnist.
San Diego, California (CNN) - When is wearing a T-shirt with the American flag on it considered provocative?
Answer: When you wear it to a high school with a dress code that explicitly prohibits "any clothing or decoration which detracts from the learning environment." And when the high school, where 20% of the 1,300 students are English-language learners and 18% come from low-income families, has been described by the San Francisco Chronicle as having "an ethnically charged atmosphere."
And when, despite concerns about potential violence, you and some of your friends make your patriotic wardrobe choices on, of all days, Cinco de Mayo.