Also, to add to Jay's instructions:

Latch the bun onto your bottom teeth and leverage the rest into your mouth, then treasure the bite you take with the contrasts of flavors and textures vying for dominance if your taste buds and tactile nerves sensing the entirety of your mouth. Key nothing distract you. Breathe through your nose still smelling the goodness in your hands. There is nothing else in the world but you and your glorious mouthful of burger.