Unfortunately, you can be fired for this. It perfectly permissable for your employer to mandate your attendance at social events outside of normal work hours. The fact is that most work relationships are "at will". This means that an employer can set the terms and conditions of employment much as it sees fit. This includes mandatory attendance at company functions. For their part, an employee can comply and attend, quit, or risk termination. As stated above non-attendence can be a grounds for termiation. In fact you can be fired for this reasom, any reason or no reason at all. Of course this assumes that you have no protection under company policy, a union or collective bargaining agreement, or employment contract.Note If you are a non-exempt employee typically paid hourly, then you must be paid for the time that you are at the even unless it is truly optional.