‘Thunder’ reigns again at box office

Weekend B.O.: 'House Bunny' hops to No. 2 spot -- “Tropic Thunder” retained the weekend B.O. crown, slipping just 38% to collect $16.1 million. Before “Tropic Thunder,” only “The Dark Knight” and “Iron Man” had managed to stay in the top spot for more than a week this summer. And only two previous studio summer titles, “Mamma Mia!” and “What Happens in Vegas,” had seen second-week drops of less than 40%.