The other night I couldn't sleep and still had my retainer in. And I somehow got the skin under my tongue (sublingual frenulum) hooked onto the side of it.
And I, like, couldn't get it out of my mouth. I was afraid of ripping it and it took a couple minutes to get it unhooked.
Just—the weirdest way to hurt myself, I swear! Have a weird nub of healing skin under there now and I don't like it.