Punching or Punch Fisting: Once one is capable of fisting, one can start to accommodate something more. The anus can become sufficiently loose to accept a fist applied rapidly. At some point the speed at which a fist can be placed in the rectum is so fast, it is almost like punching. Some women can be punch fisted in their vaginas also.
I’ve always wanted to try just ordinary fisting, but frankly, it scares me to death.