The Levi Johnston train is still going, as the 21-year-old has revealed that Sarah Palin had a cougar crush on him, E! reports.

In an interview with the entertainment network, Johnston had no objections to answering questions about anything from Palin's alleged crush to ex-fiancé Bristol Palin's intake of birth control pills.

When I was growing up, some of my friends were just like, it seems kind of weird. They were like, 'I think [Sarah Palin] likes you.' I just kept on blowing it off for a long time . . . And then my ghostwriter pointed it out to me and said, 'Hey, I think she had a cougar crush on you.' And then it all started clicking . . . looking back, and knowing what everyone's been telling me from day one, I'd say yeah, Johnston told E!

Johnston also claimed that Bristol stopped taking birth control pills to get pregnant after her younger brother Trigg was born.

It's all in the book there. It all happened on purpose, and I was just dumb enough to roll with it, he said.

The book he is referring to is his new tell-all memoir, Deer in the Headlines: My Life in Sarah Palin's Crosshairs, which was released on Tuesday.

I want to tell the truth about my close relationship with the Palins . . . my sense of Sarah and my perplexing fall from grace -- how I feel and what I've learned. I'm doing this for me, for my boy Tripp and for the country, Johnston said in April in a statement released by his publisher, Touchstone Books.

But back to the cougar crush.

She never tried to touch me or anything bad, Johnston told E!

Johnston is expected to make more media appearances in support of his new book. He's already appeared on HLN with Joy Behar, The Wendy Williams Show and a ticket-only promotional gig at the Russian Vodka Room in New York City.

Scroll down for Johnston's interview with E!