Yes, of course

Petal has chosen to replace the simple word 'yes' with 'of course'.

It can make her sound either certain, smug or plain rude.

Certain...
Me: Have you brushed your teeth?
Petal: Of course.

Smug...
Me: Did your friends like your new shoes?
Petal: Of course.

Rude...
Me: Would you like toast for breakfast?
Petal: Of course!

Will she ever just say 'yes' again?

Yes, of course she will.