When the IRS sees the type of income (lotto winnings) and the type of deductions (losing tickets) they're probably going to be a bit intrigued, to say the least. If they do some checking to find out when and where some of the tickets were purchased, it's a good bet that they're going to discover that somehow this person was able to make a horse bet and buy a lotto ticket at the same time and at two different places miles away. Babbling about this on an open internet forum doesn't help either; better just pay the taxes.