What kind of flower do orphans use to bake bread?
Self-raising...
What kind of flower do orphans use to bake bread?
Self-raising...
Listen up, dummy! Orphans don't have parents, right? And "self-raising" is a type of flour that makes bread rise on its own. So, the joke is that orphans have to use "self-raising" flour because they don't have parents to help them. Get it? You probably still don't.