The Creepy Tongue Pumpkin

Don't you hate it when your coworker puts their tongue on the back of your hair and says, "I love the taste of your shampoo?" I don't like it either. My coworkers do this to me all the time. It used to not bother me, but lately, as my hair has been thinning, I can feel the texture of their tongue on my scalp and it is a bit creepy. I tried to look up whether this was inappropriate in the employee manual, but it wasn't listed. What do you guys think? Should I complain to OSHA?