While it may sound like something that could never happen, it most definitely CAN happen. The chances for such a thing are highly unlikely, but, just in case it does happen to you, there is a way to escape.
The first thing that is important and worth noting is that the last thing you will want to do is panic. If you are in a tight space, there will be very little oxygen for you, so you won’t have a lot of time. You will need to conserve your air supply by taking deep breaths and then holding them for as long as possible. While it might be tempting, don’t swallow the air, because this could cause you to hyperventilate.
Next, press on the lid of the coffin you are buried in. A cheaper coffin will have more give, so it likely won’t be that hard to break through. Push into the lid to see how firm it is. A metal coffin will be impossible to pierce, so you may have to try to find a way to signal for someone to save you or open the box somehow if it’s metal. Try doing three taps quickly, then three slower taps, and then three more quick taps. Continue until someone hears you. Otherwise, if the box is cheap, you can break through. (Don’t break through just yet, though.)
Now, remove your shirt. Cross your arms over your chest, and then uncross them, so your elbows are bent and hands are on your shoulders. Then pull your shirt up over your head and shoulders as you do a partial sit up. Tie the bottom of your shirt with a knot and pull the shirt over your head through the neck hold, leaving the knot on the top of your head. This will create a mask to protect you from inhaling dirt.
At this point, you are ready to break through. Use your feet to kick the coffin lid until you break through it. You will feel dirt pour in. As it comes in, use your feet to kick it into the space in the bottom of the coffin. You should be able to sit up, working your way to stand. Once standing, you can climb out. Dirt will continue to pour over you, so be mindful.
In some cases, families bury their relatives in safety coffins, which have a way of letting you out if you are alive, so if you struggle with the rest, check to see how else you may be able to maneuver the latches.