Mary-Kate and Ashley OlsenMary-Kate and Ashley OlsenMary-Kate and Ashley Olsen trotted out to promote their new book in NYC.

But then the tale takes an unpleasant twist.

The girls had a nasty encounter with their ugly siblings...

The Trollsen twins.The Trollsen twinsThe Trollsen twins

Yep, the ladies had a brush with the ugly pair, who were hanging outside the shop where the girls were doing their book-pushing.

But don't think the Trollsens are a couple of nobodies hanging out for no good reason...

These two are actually doing their thing on behalf of Peta (People For The Ethical Treatment Of Animals) - beneath the masks are two animal rights protesters.

They were there to greet the girls holding friendly signs saying "Hairy Kate and Trashley Olsen: Fur Tramps" and "Trollsens: Fur Hags From Hell."

But why so grim a message? Well this ain't the first outing of the Trollsens we've seen, Peta created the characters after having issues with the girls over their use of fur.

A rep for Peta said: "From their ghoulish garb to their skeletal frames, every day is Halloween if you're an Olsen twin.

"It's frightening how out of touch Mary-Kate and Ashley are - no industry is more violent or bloody than the fur trade."

Happy Halloween ladies.