system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What causes the brain to spaz out and let me chew my tongue/cheek/lip while I'm eating food, even though I'm real good at it after so long?
gpt
Your brain does a lot of stuff in background, which takes a lot of resources (e.g. energy.)

Your brain 'spazes' out either when you are so tired/out of energy that other more important functions are given more priority (breathing >> stability) or when it tries to find ways to save energy.

That last point could be what happens: your brain has a long history of you being good at not chewing your tongue that, some times, it thinks it can be turned off and at in those times you bite your tongue (not all the times, of course.)

Also, if you are eating a lot of stuff quickly, it's harder to keep track of your tongue and you bite it.