Male Code Blue Life with Derek : Season 1 Episode 13

Casey likes Derek's best friend, Sam, who has feelings for Casey too. Derek is opposed to a relationship between his best friend and his stepsister so he tries to sabotage the possibility of them coming together by informing Sam of the "Male Code", which says a guy's best friends cannot date their friends siblings (or step-siblings). Derek tries to break Casey and Sam apart but fails to do so.