Because i have yet to get that damn thing since it was first introduce back in beta, but then again who actually has completed every achievement without them dissapearing for some reason /:
*Edit* I just became a gold digga with that post c;
pen the pig with a saddle on it in right close and smug next to the side of the hill, make sure it can fall down, and activate a piston pushing it, it can be and amount of fall damage, but I prefer having me die and see an achievement get and raw porkchops from the red background
I placed the saddle on the pig, and then lured it using Wheat to a 5x5 flat area that is 15 blocks high from the ground, then I started reducing the size of the 5x5 area to what I think it was 2x2 or less, and then rode the pig, and then attacked it. It'll panic and accidentally jump off.
Once, in an old world. I'd tried building a small dirt staircase to ride the pig off of, and that didn't work so well. So, I dug a huge pit, knocked the pig in, and got in the saddle at the last moment. We both died a horrible death, but I finally got that achievement.