What Is The Rudest Thing, Have You Seen, Or Heard Siblings Do To Each Other?

I made a hummingbird cake, and put a peice out for each child (4yo,m), (8yo,m). Oldest grandson, doesn't want it yet, so he goes and sits down. Youngest, eats his. Then, walks up to oldest, and me on the couch and says, Nia! Bubby's cake just disappeared! Really, how'd that happen? It just fell in my mouth, or something, and now it's gone! I thought my oldest was going to loose it! I readied for the assault on the younger one (referee whistle, and blocking cushion mentality.) But, I started to laugh really hard, and so did he!