Nothing silly random or fun about harboring dark fantasies of pushing people off of a cliff no matter how detestable they may be, and certainly does no honor to secular humanism. Challenge someone like Trump to a debate, give a chance to argue out his points, and if he doesn't agree to such it's probably because he couldn't rationally defend his talking points in which you'd win the debate then by default.
Such a meme could easily depict other scenarios... How would you feel if the person getting pushed off a cliff was a gay man, his assaulter being one who actually believed that the gay lifestyle was dangerous to society and that his actions were justified? I'm willing to bet you wouldn't think that's humorous, and I sure wouldn't be amused at such either. Not to mention on certain social media platforms the authorities would be contacted over what could be perceived as veiled threats. Please think about that.
If you harbor that much rage and resentment, I'd suggest consulting a therapist then, and I say that in a kind way and not to be sarcastic. Full disclosure, I don't care for the man either, but I would say the same thing regardless of the politician being depicted, because violent fantasies aren't the solution to the problems we face in society, and surely we are better than that. Then again, maybe not, maybe perhaps I'm lending far too much credit to the secular community? That said, I can understand your frustration, but there might be a better way of venting frustration is all I'm suggesting.