The heiress appears in the outrageous new film, in which comic Sacha Baron Cohen plays a gay Austrian fashionista, as part of the funnyman's ploy to make a mockery of Hollywood.
In one shocking scene, Gastineau is shown an alleged sonogram of Jamie Lynn Spears' unborn foetus. When asked if she thinks the baby looks deformed, she agrees and when quizzed over whether Spears should terminate the tot, she shouts out, "Abort it!.
But the 26 year old is adamant she wasn't taken in by Cohen's camp character - claiming she was "spoofing herself" in the comedy.
She tells Usmagazine.com, "I was joking around. I was spoofing myself.
Gastineau adds that she was at first confused at being approached by a supposed European TV presenter, but went along with it because her show the Gastineau Girls is shown all over the world.
She explains, "I was confused; I thought maybe it was still playing over there. So I was like, 'Okay'. When I got there, I saw him, and I obviously knew it was him. I was like, 'Oh, this is funny. This is a joke.' I just went along with it.
"Everyone knew I wasn't serious when I said, 'Abort a baby!' I was just playing along. Anyone who is going to see Bruno knows it's a comedy, and I was totally joking around! I was not serious.".