The `Transformers` star - who is the face of Giorgio Armani`s beauty, fragrance and skincare campaigns - admits she had an "abrasive" personality and didn`t rate her looks during her teen years.
She told MIAMI magazine: "I was never the pretty girl. [As a teenager] I was abrasive and obnoxious and felt like a loner."
Megan - who is married to `Beverly Hills, 90210` star Brian Austin Green - also enjoyed unpopular hobbies including archaeology which meant she couldn`t integrate with the popular crowd.
Speaking of her fascination with history and possible government cover-ups, she said: "I would love to go on a dig. Come on! You don`t think everything that`s learned is released to the public, do you?"
The 25-year-old actress stars in the new ensemble comedy `Friends With Kids` alongside Kristen Wiig, Jon Hamm, Maya Rudolph and Chris O`Dowd and revealed she has really enjoyed the camaraderie on set.
She explained: "I`d rather be with good people in a movie than the other way around. Most of the cast knew each other very well already - Kristen and Maya are BFFs; it was such a nice, welcoming, supporting environment.
"I always try to choose something different than what I`ve done before."