Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
There are a number of reasons why you may get called to the office over the P.A. You're either in trouble, one of the principals/secretaries need to see you, you have items in the office, etc. Last time I was called, it was because I had items to pick up.