A tiny turtle named Tate wiggles his butt back and forth as his human Crystal gives his shell a good scratching. According to commenter Turtle Trooper, the itchiness is normal when a turtle is about to shed its shell.
They get itching at times when they are about to start shedding pieces of their shell. It’s important however not to peel the pieces of lose shell off until it is almost already off because it can cause damage to the shell when done too soon. Turtles love scratches at certain times but hate having help shedding. Good thing this turtle has someone like you to care for em!?