"So I did everyone, I did the whole broad spectrum of politicians right to begin with," Sainsbury said.
"And the one that always did so well was the Paula Bennett videos. So they were the ones that like people engaged with them, shared them, and all that kind stuff, much more than all the others."
He put the research in and watched a lot of videos and interviews of Bennett to capture her essence, but said people told him they felt Bennett was a "gossipy aunty" and that's why the videos resonated, coupled with the build-up towards the 2017 election where she was frequently in the media.
Bennett said the videos never offended her, and she chose to embrace her newfound viral fame.
"I've said to you in the past that it did open me up to a generation a bit. When you go to a party and someone will come up and talk to you, literally people that had zero interest in politics would come up and go, 'Oh, you know, do you want a panini'."
"I apologise from the bottom of my heart for that, for panini and bowl lattes," Sainsbury said.
"There was about three years there like, it's not like it was just a month or two," Bennett said. "I still occasionally get the panini."
Bennett said that while she enjoyed the videos, there were moments where she began to think people were filming her and sending them to Sainsbury.
"I would literally have had a conversation in my office. I don't know why, but I remember one about a new top that I bought and my staff were like, 'Oh, that's a lovely top'. And I just picked it up as a cheapie at the weekend.
"And literally the next day, 'Oh, do you like my new top from Farmers?' I used to say, 'if one of you is a spy ...'."
Sainsbury admitted it was "a sad day" when both Bennett and Simon Bridges left politics as he had mastered them - but is hoping to work on a Christopher Luxon.
Asked if he worries about upsetting people, Sainsbury said he does.
"Like when you did a reaction video to me, I was like, 'Oh, no one will ever see any of these videos. I'll never get in trouble'. But then people watch them and stuff like that. It's like, Oh boy.
"But I think I've struck lucky for myself with politicians is that they usually have a good sense of humour about themselves. Their skin's usually tougher and stuff like that. I haven't really had a terrible reaction from someone that I've parodied before. But I have had bad reactions from fear fans and things reacting to it."
Listen to the full podcast for more from Paula and Tom, including insights on how to succeed at social media, trying to break the US, and being a Buddhist.
• Ask Me Anything is a NZ Herald podcast, hosted by Paula Bennett. New episodes are out every Sunday.
• You can follow the podcast at iHeartRadio, Apple Podcasts, Spotify, or wherever you get your podcasts.