There are really only a few valid scenarios where it is necessary to stomp someone into oblivion. This isn't one of them.

Dishonest creeps like this usually don't have a problem running to the cops when it's in their interest either, so if you're ever in the position of having to explain why you sent someone to the hospital, make sure it's something worthwhile (e.g., some drunk idiot started molesting/attacking your woman) and not something lame like having a friend who was stupid enough to be fooled by oregano.

You wanna get back at him? Spread it around that he rips people off - it'll curb his vending activities and at some point it probably will get his ass kicked. It just doesn't have to be done by you.


P.s. - Your friend needs to be told the James Murphy 5 Finger joke. Oregano looks and smells nothing like the good stuff. Was he stoned when said transaction went down?