"Why did you do that?" is what the bull seems to be saying.
Also note how the leaves of the trees have accidentally been painted over the helmets.
...And only as the third thing I realize that the bull is shitting at the two men. I'm not sure if it got stabbed because it decided to shit on someone or it shat on them because they stabbed it but in either case I don't think the retaliation is an overreaction.
EDIT: *Askold runs back to the computer* "SEE CLARENCE?! THIS IS THE KIND OF BULLSHIT THAT GOT YOU INTO TROUBLE IN THE FIRST PLACE!!"