1. To break something into small pieces with great, violent force. A noun or pronoun can be used between "smash" and "up." My father went on a rampage around the house, smashing up anything he could get his hands on. The disgruntled ex-employee stole a photocopier from the office on his last day at work and smashed it up with a baseball bat in a field beside the office.

2. To cause a lot of damage or destruction to something or within some place. A noun or pronoun can be used between "smash" and "up." He was arrested for smashing up a local bar after getting into an argument with its owner. Some punks came around and smashed my car up during the night.

3. To beat someone with brutal, violent force. A noun or pronoun can be used between "smash" and "up." The gang surrounded the poor man and smashed him up so badly that he had to be hospitalized.