I had something similar happen in a JV game a long time ago, when I was just starting out and unsure of myself. The didn't say the things repeatedly, like in Ben's story, but he did say like, "Hurt him!". It was the first time I'd heard something like that and didn't know what to do. So I simply said to his player, "That's bad advice. Don't do it." I always felt that I had not handled it correctly.
Fast forward a couple years and I'm doing lacrosse. Coach feels his kid got fouled but didn't get the call. So he yells to the kid (right in front of me
) "Get 'im in the head!" or something very similar. Flag, unsportsmanlike. I feel like I had to do it. (As soon as I finished administering the foul, he apologized to the opposing coach. He knew he'd lost it.)
We can argue about whether you toss him or just T him, but you've got to assess some foul here.