That sounds like terrible advice to me. See this for example: http://www.investopedia.com/articles/03/100803.asp
> Oftentimes, people accused of the crime claim that they just overheard someone talking. Take for example a neighbor who overhears a conversation between a CEO and her husband regarding confidential corporate information. If the neighbor then goes ahead and makes a trade based on what was overheard, he or she would be violating the law even though the information was just "innocently" overheard: the neighbor becomes an insider with a fiduciary duty and obligation to confidentiality the moment he or she comes to possess the nonpublic material information. Since, however, the CEO and her husband did not try to profit from their insider knowledge, they are not necessarily liable of insider trading. In their carelessness, they may, however, be in breach of their confidentiality.