One punch will end there fights, liver punch. Every single time one of those guys or other newbies fight they throw a lead right haymaker . Duck under it, step in and punch a shovel hook (mix between hook and uppercut) into their right ribs aka a liver shot. Most likely they would have not experienced this and will drop them the first time they receive it. This tactic I find is great for defending myself when jackasses like to swing at you just because you do boxing, you then can then trip them from this position and walk away without the risk of signifciantly hurting yourself or them. But try get to a gym mate, you will be much better for it.