"How do you beat the selfie that broke the Internet?" he wondered.
She called her in-audience selfie just plain luck that only worked because others followed her lead.
"You can't plan that. I hoped that it would happen. I hoped people would jump in," DeGeneres said. "So all you have to do is have a nugget of a good idea, and if everybody's on board and they're playing, whatever your idea is, they're with you. That just was such a perfect fluke that happened and I was so lucky."
First-time Oscar host Harris is up to the task: "Selfie's into my brain. So I'm gonna try to do something better, I think," he said.
"You can paint them," DeGeneres teased of a possible selfie follow-up.
"It's a tricky process with the content," he said. "I'm finding good jokes that we had that are funny and strong, then I'll watch a late-night talk show and they'll say the same joke … the Grammys, Saturday Night Live … I just want everyone to stop talking until Monday!"
Harris said he's hoping to strike just the right balance to amuse both nervous industry types in attendance and the millions of film lovers watching around the world.
"I'm calm, and I feel good about the content that we're doing. I want to make sure that the people that are in the theater, that are nominated, that are very nervous, enjoy the show and feel respected, like I'm talking to them," he shared.
"But I think it's more important – nay equally important – to be talking to people at home and making sure that the people, the larger group of people that are watching it at home feel that I'm talking to them and that they're not excluded from the party," he said, adding, "but if I spend too much time talking to them I'm excluding the people whose party it is."
The 87th Annual Academy Awards show will air live on ABC Sunday from the Dolby Theatre at the Hollywood & Highland Center at 7 p.m. ET/4 p.m. PT.