OK, so this might not actually be "common," but perhaps it's time we made it so: You can actually deduct gambling losses if you're itemizing. And that doesn't mean that you can only deduct losses if you're a professional gambler with a nickname like "The Scarlett Kid." (It's mine. I claimed it.)
Even casual gamblers can deduct their losses on a miscellaneous expense report; you just have to make sure the losses you claim don't exceed the amount of gambling income you report on your return. So, if you win $10,000 but lose $13,000, your deduction is limited to $10,000.
Don't think for a second, however, that the IRS won't be interested in your miscellaneous gambling loss claim: They make it very clear that you'd be prudent to keep all receipts, tickets and any other records in case they need to verify your claims [source: IRS]. In other words, trying to deduct those gambling losses might be a crapshoot.