Asking if the A B C technique is actually legit MWHAHAHAHHA

I am not experienced in any way but I am aware, there is a technique called like that lol, but the one im aware of, is with the tongue

Lol in a way yes, when sitting on it you're going to find out pretty quickly that bouncing up and down is not practical, no matter the size, it is bound to come out and your legs are going to burn 1 minute in to it instead you may rock back and forth for a easier time, also just think of the anatomical aspect of sex, the pleasure is not on going in and out but rocking upwards towards your inner walls.
Hehe