A graphic illustration of a right hand gently grasping a large arrow pointed diagonally upward. The thumb is up pointing in the same direction as the arrow. A smaller arrow underneath the hand indicates the direction to wrap the fingers around the large arrow. The title of the image is File:Right hand rule simple.png
It is funny that this gestures are taught as some kind of mnemonics, but then some for some other application another mnemonic with the opposite hand and same gesture is introduced and I don't ever remember which hand was associated with what anymore. So I remember something about hands that doesn't get me anywhere.
I believe 3D graphics uses both to describe different coordinate systems (some are left handed and some are right)
Don't even get started with y-up vs z-up