That's right. From bottle flies to coffin flies to Necrophilia americana (that would be the corpse-devouring beetles) and all their little thousands of larvae are waiting to dig into your moist flesh and eat you from the inside out. And when it comes to green bottle flies, well, let's just say they prefer their food when it's fresh, it makes it easier for them to chew.
You probably didn't realize that while you're slowly suffocating to death, your body temperature is rising to a temperature of "hot as fuck". You're panicking, possibly hyperventalating, in a very tight space with no ventilation. You don't even realize that your own breath is turning your tomb into a humid, sweat-inducing inferno.
Let's be honest, you're inside a vacuum sealed box six feet underground, your cries are muffled at best. In fact, during the 18th and 19th centuries, when defibrillation techniques and modern medicine were still in their infant stages, people in comas were often mistaken as dead and subsequently buried. ALIVE. The panic surrounding premature burial lead inventors to create a "safety coffin" so people could signal to the world above that they're still alive because no one could possibly hear them from the grave.
A rope leading from the coffin to a bell on the grave allowed the "deceased" trapped inside to alert people of their dire situation. The idiom "saved by the bell" was rumored to have come from safety coffins, but was later proved to be an urban legend.
Some might say that the worst part of all is that you're completely and utterly alone during the most distressing time of your life. But, it's not just being alone. Plenty of people die alone.
In this instance, however, you're dying alone, in a confined space with limited air in pitch black darkness with nothing but you, your dizzying panicked thoughts, and the silent earth around you. There is documentation that some people who were prematurely buried actually smashed their heads against the casket lid in order to put an end to their misery and even one story where a girl thought to have died from cholera in 1851 was buried alive and had actually begun EATING HER FUCKING HANDS. They're not sure if she did it out of hunger or terror but either way NO THANKS.
So you've Kill Billed your way out of your enclosure, but remember, you're still buried under 6 feet of densely packed soil. This means that the dirt will push down on you so hard, your chest won't be able to expand and will eventually be crushed until suffocation. And, oh, my dear child, it's not just your chest. Your ribs and head will also be crushed beneath the weight, causing bones to break, blood vessels to burst and even your eyes to pop out of their sockets. It's as if you're "literally having the life squeezed out of you." Simultaneously, your nose, mouth, and eyes are all being filled with an avalanche of dirt, cutting off your airways which will lead to brain damage.
That's right. It could be almost instant, or it can take over an entire day for you to die alone in the dark. Not to mention that every time you breathe, you're slowly converting all the air in the coffin to carbon dioxide which causes asphyxiation. And honestly, that seems pretty good, considering carbon dioxide poisoning will make you sleepy, you'd eventually fall into a coma that is followed by death.
So remember, the next time you find yourself buried alive, don't panic, take shallow, even breaths, and make peace with your inevitable doom.