Because he doesn't have arms. Knock knock. Who's there? Not Joey.
Bob
Rustle
Peter Parker can swing a web. Clark Kent.
Me: why Him: Timmy has no arms. Knock knock. Me: Who's there Him: Not Timmy.
He had no arms. Sorry that joke was stupid, let me try again. Knock Knock "Whose there?" Not Billy
It doesn't make sense, he and all his friends are always stuck in second gear