Jamie-Lynn Sigler and Jerry Ferrara Jamie-Lynn Sigler and Jerry Ferrara

The rule of thumb for interviewing is to do your homework, but ABC anchor Dan Harris' dog clearly ate his assignment notes for his sit-down with Jamie-Lynn Sigler.

While casually interviewing Sigler — who is Jerry Ferrara's girlfriend in real life and plays his character's girlfriend on Entourage — Harris, clueless about the Sopranos star relationship status, asked Sigler if she thinks "beautiful women do or would date fat dudes."

Check out photos of Sigler and Ferrara on the red carpet

Sigler, a good sport, cracks up at the question, causing Harris to follow suit. She tells him her boyfriend is not fat, and Harris remains clueless. When Sigler finally tells him she and Ferrara are together, all Harris can say is, "Wow, I really stepped in it." He later apologized to both.

Check out the interview below: