They said they've had to cover for dad when he broke any of mum's rules, like that time when he was instructed not to use a chainsaw to cut down a tree they had in the backyard.
Simon decided he'd use the chainsaw anyway and ended up cutting through the main water pipe into the house.
"Dad, of course, not wanting to get in trouble with mum, yelled out for me, 3 years old.
"First thing he yelled was 'don't tell mum'," Samantha shared.
Sophie said one of her favourite memories was of a spooky rollercoaster ride she took with dad while on holiday in Australia, despite mum not finding it a very good idea.
It turns out mum was right again and Sophie was terrified during the ride and ended up in tears. Simon sees his wife approaching and throws Sophie into the bush telling her "I'll give you an ice cream if you stop crying".
"We really love you, dad, and you've definitely had our backs over the years," Sophie added.
"We really appreciate everything you've done for us girls."
A clearly emotional Simon Barnett wished a happy father's day to all Kiwi dads.