Shia LaBeouf blames his drunken trespassing arrest in November on an unexpected pimple on his forehead.

The actor was booked after refusing to leave a Walgreens store in Chicago, Illinois in the early hours of November 4, after drunkenly trying to buy cigarettes.

And the 21-year-old insists the whole incident could have been avoided if it hadn't been for an outburst of acne - and a mocking security guard.

He says, "I got pretty drunk and needed some cigarettes, and on my way down the elevator, I'm feeling my forehead and I feel this pimple. So I go into Walgreens and I go to the cosmetic aisle and get some pimple cream and I see a security guard and he's looking at me... and he's kind of giggling to himself. I'm starting to feel like, 'Look, it's really not that funny.'"

LaBeouf recalls buying the cream and returning to his nearby hotel, only to realize he forgot to pick up cigarettes. He changed his outfit, so as not to be recognized by the snickering security guard, and returned to the store.

Forgetting the cigarettes again, the actor had to make a third trip to Walgreens, which raised the guard's suspicions and he called the police.

LaBeouf was not charged in the incident - but he had to deal with an angry Steven Spielberg, the director of his new movie Indiana Jones and The Kingdom of The Crystal Skull: "He said, 'Smoking isn't just bad for your health, it's bad for your reputation.' That was not a great call."

-Shia LaBeouf Pictures

(This news article provided by World Entertainment News Network)