It appears to have been a Christmas bonus. You are an employee. Despite the fact that it was issued outside the regular payroll check system, your employer should have included it in your W-2. It is not your responsibility to "guess" if it is included or not. It is not reportable as tips, and you should not file Form SS-8 to determine your employment status.
You are an employee, you received a proper IRS form W-2 for your wages. Unless you feel there is an error in your W-2, you should file your taxes with the W-2. The Christmas bonus does not come into play when doing your income taxes.
