See subject. Thought of this by minute eight of non-stop licking.
On a ferret, the height of the filiform papillae (the rough stuff, most of the tongue) ranges from 60-175 micrometers; diameter 90-175 micrometers of keratinous squamous cell. Couldn’t find for dog on-line, after 20 min research time.
Call the surface are 6-cm2. Need strength of materials and of muscles for dog, ditto human.
Your check? 
Cheek. It’s 4:30 AM. I should be asleep.
Hmmm. I’ve heard of dogs with doggie OCD licking through the top of their paws to the bone, so it’s possible.
I know a cat could do it. I woke up one night to Neon washing my forehead… It hurt! He had licked off the first layer of skin and left me with a “lick sore”. His tongue was rougher than his any cat I’ve known. I don’t usually mind being licked alittle…lol. He finally figured it out and tried to be gentle. But he’d lose it a few licks later. He’s do lilke 3 soft licks and then tear your flesh off with the third one. His sister is obsessive about it, but gentle. She’s a arm and neck licker.
<just saying, but…>If you signed up as Guest for this one reply I think that’s pretty cool.
Ah-1, ah-2, ah-3, CRUNCH
Three. Three licks to get to the center of Leo Blooms skull. relevant commercial
(I hope it’s not too soon for a jokey GQ answer?).
Beat me to it, first thing I thought of. If it makes you feel any better Leo your not alone. Gunner the Great Dane seems intent on licking me to death. I have never considered that he might lick his way through my skull, so thanks for implanting some additional nightmare fuel into my brain!
Is it certified?
I’m glad I’m not the only one…!
As Janeane Garofalo’s character said in The Truth About Cats & Dogs, “Let’s talk about boundaries. We can love our pets, we just can’t LOVE our pets.”