Step 1: Not to be confused with...
The "Rock On"sign is not to be confused with the sign for "I love you" in American Sign Language, which is made by also extending the thumb, or the shaka sign used in Hawaii, which is made by extending just the thumb and little finger.
Note the picture of the female who is attempting to show how much she "loves something" with not one, but two hands. Obviously all of her love could not contain her tongue. I suppose that heart on her chest is most appropriate.
Step 2: Learn it
If you are one who believes Bush isn't rocking like a rocker please compare his flawless technique to that of its alleged creator Ronnie James Dio, who is also pictured below.