When my brother and I are playing with Legos, we build towers and cars for the good guys and the bad guys. When the bad guys are fighting, they always seem to be the ones blowing up! Their is physics when my little brother smashes my wall with his fist because he is applying force to the legos so that they move. However, if he punchs the legos vertically than he is going be applying force to the ground as well which is much more stable so punching it this way will hurt! This is because when you apply force to something, that same force is applied to you!
Additionally when we are cleaning up and we are throwing the legos back into his box it crashes and makes lots of great crunchy sounds! I hypothesize that the sound will change based upon how hard something is thrown because the contact between the objects happens at a higher rate when thrown faster so it emits a louder sound!