depends on how you contact..
you can use your body to 'bump' the guy into another direction
without mowing the guy down..
then defense also.. you can 'take a charge'.. the guy comes
bearing down on you, you hold your ground if your feet are
planted.. the guy runs into you, it's an offensive foul..
no hacking of the arms/hands..
fun 
ya, some guy was bumping into me aggressively before
i was just standing there thinking "wtf is he doing?"
on the field i'll just wait for a chance to slide for ball and
making him feel it... and no free kick for him. hahahahahaha~
