"People just think that when you're pregnant, they get to say whatever they want to you and it's a free-for-all. It's hurting my feelings and getting a bit too much," she said on her husband's 2Day FM Hughesy, Ed and Erin breakfast show on Wednesday.
"Everyone's just like: 'Oh my God, you must be about to pop, you're massive, you're enormous, you must have three in there'."
Ed said he had witnessed some of the insensitive comments his wife has copped since falling pregnant for a second time.
"We have had two men in public say - while I'm standing there - to my wife: 'You're massive. You're massive'," Ed said.
"A man in a café said to my wife: 'You must be having a girl 'cause she's stolen your looks. My wife, she had three girls and all she had was a tiny basketball, but you're massive."'
Tiffiny said she was shocked that strangers had the nerve to comment on her body, and wished Ed had said something to them.
"Ed didn't do any Will Smith action at all!" she said.
"You didn't do anything, Ed! I was dying, I actually cried after that. I got in the car and I had a cry."
Tiffiny and Ed, who share four-year-old Arnold, announced they were expecting their second child in December.
In February, the 37-year-old said she's felt the pressure so many expectant mothers face to look a certain way.
Tiff described the look as "skinny legs and a perfect bump", but says that women – herself included – shouldn't have to deal with the unrealistic beauty standards around pregnancy.
"I feel okay, I do," she told Today Extra hosts David Campbell and Sylvia Jeffreys.
"But … there's a lot of pressure to feel a certain way and be a certain way when you're pregnant, and also so much pressure after you have the baby to 'bounce back'.