Godwin's Law: If an online discussion goes on long enough sooner or later someone will compare someone or something to Hitler or his deeds.
MN Godwin's Law: The more fractious a debate gets, and the more fierce the disagreement between posters, the more certain it becomes that someone will say another poster is "sad" and "has no life" because they're invested in a forum discussion. Crucially, the person making the accusation will see no irony in this.
Happens a lot, no? What should we call it?