These are the currently legal body parts to aim at:
chest, stomach, r_arm, l_arm, r_leg, l_leg, r_hand, l_hand, r_foot, l_foot, head, random
In the future, there will be conversion for some monsters (a snake with a right hand is very funny but not really realistic!!).
By choosing random, it's randomized, but one important thing to know … some monsters have weaknesses ;).