lol, well this quote is reported to come from her 2008 GQ magazine interview
"If you eat Chinese food, your farts come out like Chinese food. If you eat Mexican food, your farts come out like Mexican food. And milk, it's like—you can smell the warmth in the fart."
http://www.eonline.com/news/137374/top-9-best-things-to-come-from-megan-fox-s-mouth
But reading the context of other things she has said such as this to Esquire...
"Let me tell you what it's really about. High School Musical is about this group of boys who are all being molested by the basketball coach, who is Zac Efron's dad. It's about them struggling to cope with this molestation. And they have these little girlfriends, who are their beards. Oh, and somehow there's music involved."
It can all be her trying to be funny and her sense of humor is dark (I mean she was dating a Goth Rocker) or just saying things to appear to be unsexy. Other celebs have done the same thing, I remember Rihanna talking about farting in an interview.
Who knows really. I knew gross girls and girls who lied about being gross to appear unsexy.