I was reading William of Orange's Wikipedia page when I stumbled on this excellent (and well-cited, if you click through to the original) paragraph, which is about his suspected gay lovers:
Bentinck's closeness to William aroused jealousies, but some modern historians doubt that there was a homosexual element about their relationship. The same could not be said for Keppel, who was 20 years William's junior and strikingly handsome, and had risen from being a royal page to an earldom with suspicious ease. Portland wrote to William in 1697 that 'the kindness which your Majesty has for a young man, and the way in which you seem to authorise his liberties ... make the world say things I am ashamed to hear'. This, he said, was 'tarnishing a reputation which has never before been subject to such accusations'. William replied, saying, 'It seems to me very extraordinary that it should be impossible to have esteem and regard for a young man without it being criminal'.
The first part I like is that he was doing a page, which just goes to show that Mark Foley wasn't doing anything original (even for the US Congress).
The second is that, when confronted with the allegations, he proves that the phrase "so much fun it should be illegal" dates back to at least 1697.