When a Ham is a Roast

"Rabbi, you must help me! I bought a roast, but when I brought the package home and opened it, I found a ham!
Two packages must have gotten switched... We're really short on cash
and this roast was supposed to last us until payday. What can I do?"
"Go ahead and cook the roast."
"But I just told you, it's a ham!"
"Don't worry. God will understand. I promise you, this one time, the traif is kosher!"