Trolling his yukkuri fatally? In my experience with images on this site, abyusive owners tend to go for some real misery instead of such a quick (albeit painful) kill.
Why so serious coker? the possibility exist since we only see a manjuu eating rice cake and then getting trolled and killed either it was a well placed trap or the legitimate owner of the rice cake punished it in the way yukkuris usually get punished.
It doesn't matter anyway, it was a joke, and you seriously missed it, and man, it wasn't even a sarcastic one.
It's like when one says "that happens when you run around with sharp objects" on a pic on which a yukkuri got stabbed by a sharp object and nothing else is there, no mister, nothing.
It's the same situation here, the yukkuri was eating a rice cake, and the mister got on her case, so one could joke about that rice cake being the mister's and that action being the punishment for eating it, clearly not meant to be taken as what the comic scenario really is but a humorous thought.