I don't know if it's programmed in or just cargo culting but if Siri accidentally triggers and starts talking to you, "Nobody asked you Siri" is my favorite way to get it to stop interacting.
Said in the tone of Cobie Smulders in How I Met Your Mother (Nobody asked you PATRICE!)
Said in the tone of Cobie Smulders in How I Met Your Mother (Nobody asked you PATRICE!)