In response to Tails; good question.
I once asked my English teacher at school why if you had a dog called "Spot", then substituted with "it", where does the apostrophe go? For example:
"There was a bone in Spot's mouth"
"There was a bone in its mouth".
The way she explained it to me was that you don't put an apostrophe in "my", "his", "her", etc..., so you shouldn't put one in "its". Thing about it as a whole word in its own right...
I suppose if "It" was the poor mutt's name, that makes it a proper noun, in which case I guess it would be:
"There was a bone in It's mouth".
...but I think we're being picky. Unless of course you happen to be a Stephen King fan with a penchant for the canine world.
It's a funny one, but that's the English language for you.
IRO the "Had Had" puzzle, I gave up and googled it. Can't say I was anywhere near. My idea was that one of them had the surname "Had-had-had", but I was way off... I won't ruin it for anyone, but it can be done!!