I once mentioned on Usenet that I had a Plecostomas catfish die in my aquarium. Somebody else remarked theirs was fine. Shortly after, theirs died. Somebody else said their pleco was fine they had no problem keeping them alive. And then it died. After this happened a few times I point out that every time people bragged about their Plecostomas catfish on Usenet, then that fish would die a short time later. Similar to the way Macbethis called "The Scottish Play" to avoid the bad luck of actually saying the name.
People began writing "pl*co instead of pleco to avoid the dreaded usenet-pleco curse.
That much I remember. I don't actually remember who spelled it "pl*co" first; it might have been me but probably not.