If you don't believe in a path to citizenship for undocumented workers, then you have NO RIGHT to celebrate Cinco de Mayo. I venture to say most of the people celebrating Cinco de Mayo are white people with nothing else better to do. They probably get drunk several days a week and complain. Likewise, I doubt they want Hispanics and Latinos, who are undocumented, to be lawful permanent residents or citizens. If they were, then they would take jobs away from the white people who celebrate Cinco de Mayo and get drunk on a Monday-- the real winners in our society.
So my advice is simple: if you celebrate Cinco de Mayo tonight, you better be in favor of a path to citizenship. Otherwise you are un-American and probably deserve to lose your job to a Hispanic or Latino. Don't try and claim you work harder because you are drinking (or considering it) on a Monday night.