For this instructable, you will need a cutting board, a kitchen knife and an apple.
Optional: BBQ sauce (the more red it is the better.)

Step 1: The Eyes

Cut the apple in half and take out the seeds. Then stick the knife about three millimeters into the apple where you want one of the eyes to be and spin the knife. Do the same where you want the other eye to be. Now, take two of the apple seeds and stick them where you wanted the eyes to be.

Step 2: Eyebrows, Mouth and Nose

Carve the eyebrows, nose, and mouth. The nose should be triangle, the mouth should be a circle or an oval and the eyebrows should be diagonal slants right above the eyes.

Step 3: The Teeth

Stick two more seeds in the mouth. One on the bottom and one on the top spaced away from each other a little bit.

Step 4: The Grand Finale

Now for the fun part, stick the knife where ever you want it.
Optional step: for the bloody effect you can dip the knife in BBQ sauce.
You are now done!