code:

// Add the "JIGGLE" keycode to the list of custom keycodes
enum custom_keycodes {
  QWERTY = SAFE_RANGE,
  NUMPAD,
  LOWER,
  RAISE,
  ADJUST,
  JIGGLE
};

// Put the "JIGGLE" keycode somewhere on your layout, you choose where. 
// In my case I put it on the ADJUST layer

// We'll use this variable to track whether the jiggle is on or off
bool mouse_jiggle_mode = false;

// This is the desired jiggling behaviour, the mouse and scroll wheel move 
void matrix_scan_user(void) {
  if (mouse_jiggle_mode) {
    tap_code(KC_MS_UP);
    tap_code(KC_MS_DOWN);
    tap_code(KC_MS_LEFT);
    tap_code(KC_MS_RIGHT);
    tap_code(KC_MS_WH_UP);
    tap_code(KC_MS_WH_DOWN);
  } else {
 }
}

/* at the end of your keymap file you'll find a switch statement that handles different layers. add this case block to the switch statement. it toggles the mouse jiggle mode on and off */
    case JIGGLE:
      if (record->event.pressed) {
        if (mouse_jiggle_mode == false) {
	  mouse_jiggle_mode = true;
	  return false;
	}
	if (mouse_jiggle_mode == true) {
	  mouse_jiggle_mode = false;
	  return false;
	}
      } 
      return false;
      break;