The WOW factor is always appreciated by bored family member before and after a holiday meal.  Prior to the meal, everyone is waiting and starving and told to stay out of the kitchen.  Captive audience there, but an even MORE captive audience is AFTER the meal, when everyone has eaten themselves into the inability to move.  Don't bust a move, bust an apple, into perfect halves.  EASY!

Basically, remove the stem.  The base of your thumbs will go where the stem was, find a comfortable spot around the stem hole.  The rest of your fingers will naturally fall down around the bottom of the apple.  Then apply pressure while you're rolling thumbs out. That's the force that will split the apple open.

Confusing?  Here's the video to put it into prospective for you.  Let me know how many times you had to practice to master this phenomenon.