Tween/teen Disney Channel original comedy series, airing from 1999-2003. Staring Shia LaBeouf (Disturbia, Transformers) as Louis Stevens & Christy Carlson-Romano (Kim Possible) as Ren Stevens.
The series centers around Louis & Rens' bickering as brother and sister.
Do you remember that episode of Even Stevens where The Twitty-Stevens Connection played a concert on the school roof?! It was hilarious.