The candy company M&M Mars can print custom lettering and designs on their M&M's, for a price of course.  The one caveat is that you can't print any obscenities or objectionable content.  One might ask, "What's the point of custom printing if you can't print obscenities?"  But Mars is a wholesome company, and as their hard-to-find Do's and Dont's page says:  "We don't want to leave a bad taste in anyone's mouth."  Apparently they're ok with bad jokes. 

I happen to know someone on the inside, and the unofficial word is that the company employs three old ladies as obscenity checkers.  Sometimes they catch things before they're printed, other times they don't.  This was one of the things that was deemed unwholesome, but before the entire batch was dumped in a pit of bubbling sulfuric acid, a few found their way into my hands.