More than just your friends are following you on twitter and facebook. CRA can and does monitor social media and will use the information you post as part of a tax audit. They will also demand info from shared economy operators such as ebay or airbnb to make sure you are reporting all of your income. A CRA voluntary disclosure can avoid prosecution and penalties if you have evaded tax.
"This article provides information of a general nature only. It is only current at the posting date. It is not updated and it may no longer be current. It does not provide legal advice nor can it or should it be relied upon. All tax situations are specific to their facts and will differ from the situations in the articles. If you have specific legal questions you should consult a lawyer."