In the original scene, these two characters, Trish and Mista swap bodies. Mista while in Trish’s body does some really unladylike things like spit, and unconsciously scratch his crotch, which really bothers Trish.
Now we’re getting the gender swap version with boy Trish and girl Mista. I guess even as a girl Mista is still really uncultured and picks Trish’s nose while in his body, upsetting him.