This is one of the coolest optical illusions I’ve seen (a bit tough as well).
Most people will see the girl spinning clockwise initially… but the girl can be seen as rotating anti-clockwise as well, depending on how you see it.
Tips - focus below the hip to ‘change’ the direction; if you still couldn’t see it after some time, cover the upper body part and just focus on the legs.
[Hat tip to Moillusions]