From NBC New York...

"American judo fighter Nick Delpopolo was expelled from the Olympics for doping Monday, saying he unintentionally ate something before the games that had been baked with marijuana.

Delpopolo is the first of the 10,500 London Games athletes to fail an in-competition doping test. His case is the fifth positive test for a banned substance reported by the IOC since the Olympic body started its London testing program in mid-July. The other four were caught before competing..."

Link to the entire story from nbcnewyork.com: http://www.nbcnewyork.com/news/sports/NATL-American-Judoka-Expelled-from-Olympics-for-Doping-165129016.html