The Hills star Spencer Pratt has hit out at Mary-Kate Olsen - after she joked about his temperamental days on the high school football field on a U.S. TV chatshow.

Olsen laughed about the reality TV star's bad temper when they were classmates while chatting to U.S. talkshow king David Letterman, saying: "He used to play on the soccer team for my high school and he does not have a good temper."

But Pratt was left fuming by the live TV remarks, bitterly telling reporters he knows he has made it in Hollywood now a "famous troll" has commented on him.

And he further lashed out at the 22-year-old actress - insisting he forgives her as she has endured a "tough" life as the less attractive twin - comparing her to her sister Ashley.

"(Mary-Kate) should probably focus more on not getting dressed in the dark than on me. I forgive her, though. She's had to go through life as the less cute twin, which must be tough."