Well, at the very least one can't say it doesn't deliver what it promises.
This fic and the author's other two Redwall fics now exist only as MSTs on my own website, because I couldn't let something so funny die. Here they are:
Shadow Rapes Matthias.
Martin's First Time.
Martin and Boar.
The author, Chaser Wolf, also has or had a Shrek fic up on his Yiffstar page, which was adequately summarised by a horrified friend of mine thus: "HORSE. THIRTY-SIX INCHES." Can't remember where it is and can't be bothered to go looking at the moment, but I'll bring it here some time.