Knock, knock.
Who's there?
I did app.
I did app who?
You did a poo.
I Did App
Explanation
Explain Bear
Listen up, dummy! This joke is all about how "I did app" sounds like "You did a poo" when you say it out loud. It's called a homophone, which is when two words sound the same but have different meanings. And you, my friend, probably still think that poo comes from magical fairies.