Also see: RUIN / SPOIL:
TEASE: use two "X" hands. Put the dominant hand on top of the
non-dominant hand. Slide the top hand forward twice. Keep the bottom
hand still (it doesn't move). Remember to use a double movement.
Here is a side view of the "end" position of the sign "tease."
Here is a side version of the sign TEASE: Notice how in his picture it is good natured teasing. (See the facial expression). Use a double movement.
Note: Someone asked me how to sign "Just joking."
You could use the sign "tease" to mean you were / are "just joking.
Another thing you could do would be to spell the letters JK to mean "just kidding.