And you thought legal history was tame. Mingle2 gives The Legal History Blog an "R" rating because of the appearance of these words:
murder (5x)
dangerous (2x)
pain (1x)
And they seem to have misconstrued a nickname for "Richard," which appears 3 times, e.g. in a reference to the Vice President. But the search engine missed references to torture and other matters. Words like this have led other law blogs to be rated NC-17, including this, this and this. Lots of history is, apparently, not for little ones. Cliopatria is also rated R. Hat tip.