Life with Derek - Season 1 Episode 2

Derek manages to insult his new step-sister, making Casey clumsily fall down at school and earn the nickname Klutzilla. And it just keeps getting worse as Casey continues her klutz streak. Finally Derek realizes something, besides his rude behavior, that might be making Casey fall and decides that helping her reputation will help his, as it's bound to get out that they are newly step-sibs.