Transcript:

Shermy and Patty sit on the floor playing. He says,"Somebody's at the door"

She walks off saying,"I wonder who it can be?"

She opens the door and sees Charlie Brown. She says,"Oh, it's you, Charlie Brown..."

He looks at the reader as she walks off saying,"I thought it was somebody important!"

The gag is recycled from the Li'l Folks strip of December 24, 1947: