There are several ways that you can get yourself sick. You can induce vomiting by consuming a lot of fluids such as water, milk or both. You can also stay up all night and as a result, your eyes will be puffy in the morning, you will have dark rings under them and by coughing through out the night, your voice will be husky in the morning. These will help you fake sickness. You can also get really drunk as a hangover normally has the same signs as the flu. However, it is not advisable to do any of the things listed above as they may be detrimental to your health.