You’re in luck! The Kennedy half dollar, minted since 1964.

I think the word ‘conspiracy’ here is being conflated to mean ‘ridiculous, and false, conspiracy theory’. Conspiracies happen, but the word itself has the association with those who theorize and speculate on the absurd. I can say I don’t know for sure what the original commenter meant, but I think it is implied they meant they ‘know the Clinton’s murdering people isn’t true’.