I don't know about the cartoon, but it can also be interpretted as cunning plan of the rabbit.
So it could be a playword if for instance, the rabbit is trying to suicide with a very clever plan (or you are trying to kill the rabbit).
As Romain Valeri said, the "coup du lapin" is well known when we talk about breaking neck on car accident.
I saw an exemple here : (I typed "coup du lapin cartoon" on google)
It looks like this is a website with many cartoons about a rabbit trying to suicide. It would so be a wordplay about the rabbit doing a clever plan and dying quickly