Imagine Person B leaving the couch for a second and Person A grabs the bag of skittles out of the couch and pours it in  B's bowl of M'Ms. 

B comes back and sits down with A. A quickly hides the skittle bag watching B grab a Skittle or M'M to see their reaction. 

(B hates skittles) 

B spits out the skittles hearing A laughing their ass off. B grabs the bowl and throws it at A's face.