The definition of 'bes dum' can be applied to anything in this world that a person can form an opinion on.
Derived from lazy internet lingo and poor grammatic usage, 'bes dum' is a term that English teachers would frown upon.
Normal: "That was movie was just bad."
Usagee: "That movie bes dum."
Normal: "George Bush in an idiot."
Usagee: "George Bush bes dum."