It'll hurt *you* if they find out and decide to press charges.
Brings up a good point..have you (or anyone on this forum) ever heard of this actually happening to someone? I haven't and I've been doing it for years.
I shipped three cases of beer from a monastery I wont name in three different boxes back from Belgium this year and a fourth box full of beer from Paris. All via USPS, once it was stateside, and all arrived at my local post office. Only one box was damaged so bad that a few of the bottles broke. When I picked it up, they'd wrapped it in plastic and it smelled horrible. They kept asking what it was so I finally said something about cooking supplies, vinegar, etc. The spine was busted on another box and was so bad that you could actually reach in and pull out a bottle; surprisingly, they were all accounted for, though! Anyways, no issues at all. For the record, the Belgian post all but gave me their blessing, however, the French were freaking out because I didn't have a French return address..eventually, they let me ship it after a bunch of dirty looks. Not once did they question what was in it, they just wanted to make sure it said something on the forms; I used "Souvaniers/Personal Purchases." I will say that a worker at a different Paris post office than the one I used told me specifically that they would ship wine/beer to anywhere in the world...except the USA. They even have special boxes for it. The price to have shipped all that back internationally with UPS or Fedex was completely prohibitive; their prices were astronomical compared to standard post.
I've also shipped plenty of beers nationally to competitions and never had an issue. Really, who has?