What are the consequences of lying to the US Post Office about the contents of a package (specifically, the presence of alcohol)

I was trying to ship my friend some homemade beer as a gift. Completely legal, completely safe. No law against it in either of our jurisdictions. Seems the US Post Office has a policy against shipping alcohol, even when it’s legal in both places. They allow shipment of non-alcoholic beverages, but not alcoholic ones. Being that shipping alcoholic beverages is no less safe than shipping alcoholic ones, I can only assume this is one of many laws/ules that can be safely ignored from a moral standpoint. As far as I know, there is no US federal law prohibiting this. However, from a legal standpoint, what are the consequences? Would they x-ray the package and see something that looks suspiciously like a beer bottle? I can only imagine this policy exists because of the Wahhabi Protestant ethos that pollutes many United States institutions.

(If you must know, I finally just went to UPS rather than going to another Post Office and lying about it. But that was just because UPS was closer, and they didn’t care one iota what I was shipping.)