A Twitter account associated with hacker group Anonymous appears to be taking responsibility:
The fact that it's a national holiday probably didn't help matters: The hack has been going on for over an hour, and the BK press office has not been responsive. Update: After an hour and fifteen minutes, the account has been suspended. The account, at the time of closing, had gained over 30,000 new followers.
A Twitter spokesman says, "We don't comment on individual accounts for privacy and security reasons." Burger King has released this statement:
It has come to our attention that the Twitter account of the BURGER KING® brand has been hacked. We have worked directly with administrators to suspend the account until we are able to re-establish our legitimate site and authentic postings. We apologize to our fans and followers who have been receiving erroneous tweets about other members of our industry and additional inappropriate topics.