From UrbanDictionary: Punching down: For someone of higher rank, power, status, and position to engage someone of much lesser and/or inferior rank, status, power, and position in debate and/or argument. Not limited to just status, power, position, and rank but can and often do include intellect, capability, competence, and acumen.
Oh, actually, hmm... that last part (not including intellect). Maybe you're right after all. Except for the isn't funny part.