Various Situations When One Needs to Scratch and Might Cause Bleeding;
understanding the two views with "דרך לכלוך" (coloring destructively). (Wiping one's hands on a towel from grape juice, blood, pomegranate, colored ices, etc.);
(Squeezing materials.) understanding the concept of squeezing out human hair, toothbrushes, baby bottle, etc.;