I have a hole directly behind my two front teeth. It's a hole in the roof of my mouth. I can't feel it with my tongue, it's so small, and I can't see it, but I can suck air out of it by closing my mouth and sucking towards the front of my mouth. I can also push air out of it by holding my nose while blowing out (as done on an airplane), which clogs my ears, naturally. I can't always suck air out of it, but I can always push air out using the method of holding my nose and pushing out air without letting it out of my nose or mouth. The taste around the area when this is done is similar to the taste of blood, but when I wipe the area with a white tissue, nothing shows on the tissue. If it wasn't for me making a suction in my mouth in a certain way as I knowingly do now, I would have never known the hole was there, but I've known about it now for a year.