In the first debate, Mitt Romney pleaded ignorance about the tax credit for companies which move US jobs overseas, joking that maybe he needed a new accountant. But, wait, isn't this the same Mitt Romney who has a proven track record of sending US jobs overseas? And isn't this the same Mitt Romney who claimed it would be irresponsible of him to pay more in taxes then he has to under the law?
Aha! Mystery solved. The reason Mitt Romney is keeping his tax returns hidden is because he has shipped US jobs overseas and then personally pocketed tax deductions for so doing. Perhaps he has taken this same deduction six, seven, eight times, which would account for all those years of tax returns he's keeping hidden.