BAD idea......
If for any reason you are audited, they will see income much quicker than they will see expense from previous years and either way its tax evasion....
So year one you "loose" 10K
Year two you make back 5K
Year three you Make 10K
Unless this is all cash, not checks, paypal, money orders or credit cards, it will hit your account. IRS will then see the $15k came in and you only reported 5K.
Show your lose, show your earnings.....