Peel your hard boiled egg and put the yolk into your ziploc bag. Reserve the white.
Smash up the yolk, squish it!
Add mayonnaise, mustard, salt and pepper. Smash until evenly combined.
Cut a corner off the ziploc bag. Squeeze the contents out into the egg white. Enjoy!
I give credit for this idea to my friend Ongelique from my church! Brilliant!