hardlogic
I turn around once. What is out will not get in. I turn around again. What is in will not get out. What am I?
Common Wrong Answers
“A door”
While a door can open and close, it doesn't 'turn around' in the way described in the riddle. A key physically turns to lock or unlock a door.
“A lock”
A lock does secure what is inside or outside, but it does not 'turn around' itself; rather, it is the key that turns to operate the lock.
“A safe”
A safe holds items securely and can be locked, but it does not turn to control access; it is the key that turns to lock or unlock the safe.