Remember Rick Perry’s “oops” moment? Turns out he was hopped up on painkillers:

Texas Governor Rick Perry’s famous “oops” moment during one of his last Republican presidential debates was just one highlight of his often confused campaign across America. It was reportedly made possible by the heavy, deadening influence of prescription painkillers, according to a forthcoming book by two well-sourced reporters.

The claims are made in a forthcoming book by reporters Mike Allen and Evan Thomas, according to excerpts provided to the Republican-leaning Daily Caller website. The book is called “Inside the Circus,” and it aims at providing a behind-the-scenes look at the Republican presidential primaries.

The Texas governor’s drug use wasn’t just the cause of a single humorous, highly embarrassing moment, they add. In another instance, a rival campaign’s manager reportedly walked in on Perry while he was urinating… and singing “I’ve Been Working on the Railroad” at the top of his lungs.