It is impossible for most people to lick their own elbow. (try it!)

[Rikimaru]

Also at the back at you head. You can't also lick it!

 

[YvanaStarr]

nah.. tried it long time ago.. you really can't lick your own elbow. Unless, you have a long tongue that extends.

 

[Kaiser]

Challenge accepted! BRB, gotta contort myself into a human pretzel haha