Peetah, What is the joke here?

Help

welp, i dont get it

Sharps flats and natural notation but that is all I know about this. Please enlighten me on this

Petah please help me

How come gregly aint used anymore

Why is this bad?

Help me petah

What does A11 have to do with markiplier? I know its something about the pronounciation but I cant figure it out

I’m confused

Is this a reference to something?