She is the girl in-between television's laziest, rudest, bong-smoking dog and her hapless boyfriend.
The show returns with a new series after being absent from our screens for nearly three years.
"It was a nervous wait for me, wondering if they were going to do it again," says Waddingham. "But I was very excited when they eventually did call and say 'Yep, we're on!'"
"I met Tony and Adam when I was doing a commercial with them, so that turned out OK," she says.
"Then I went and auditioned for Wilfred, but they had a lot of glamorous girls auditioning and I thought, 'There's these lookers, so they will probably go for them'. But they obviously wanted something different."
In Wilfred the dog talks only to Sarah's boyfriend Adam (Zwar) and not to her, leaving her with a most unusual job description as she tries to visualise only a four-legged friend and not a guy in a mangy dog suit.
"It's a little bit strange. Every so often you take a step back and think, 'I can't believe this is my job'. You come to work and there's a guy in a dog suit making a cup of tea off to the side.
"You try to ignore the fact that he is talking to Adam," she laughs.
"They get me into a little bit of trouble sometimes before a take, because they'll be doing a little comedy routine just before they say 'Action', and I'm about to piss myself laughing. They're good fun."
The very humble Waddingham isn't yet sure whether she will be sitting down to watch the premiere with friends.
"I can't stand watching myself," she admits.
"I watched the first series and thought 'I can't believe they let me be a part of this'. But I really love watching the boys so I'll definitely check it out just for that and close my eyes when I'm on screen."
Wilfred airs 10pm Mondays on SBS ONE.