Lip Window
The labret is a fairly common piercing, one which is beneath your lower lip and is often seen as a stud or spike. It’s so common, you probably know someone who has one. This is what happens when someone stretches their labret piercing as they would their ears and after it gets big enough, they stick a pyrux plug in it. You get a lip window. (Source)
All I can think is that you’d have to be worried about food stuck in your teeth 24/7 D:
Fibromyangela 