I'm thinking of pushing a homeless guy into a dumpster
Why do you want to push him into a dumpster.
I saw him eating dog food.
Violence is never a solution and thinking about pushing someone based on what you saw them eat is troubling. Instead of hurting the person, why not bring them a meal from a restaurant so they don't have to eat dog food?
I don't care about them.
Well even if you don't like homeless people, you should never use violence against them. Try to put yourself in their shoes.