Charlie Munger's Berkshire AGM zinger for "ridiculous" Elon Musk: A "moat" is not a puddle.

Plenty of people love Elon Musk for iconoclastic style and his refusal to play by the rules in business. But sometimes, sense is more important than style. Lately, perhaps feeling the pressure of Tesla's growing pains, Musk's behaviour has been a little more wacky than usual. As Tesla groans under the weight of growing debts, Musk's jokes about bankruptcy fell flat, and his strange behaviour on Tesla's recent earnings call (combined with some weak numbers) saw the share price plunge. Now, Musk seems to have stumbled into a mini-feud with the investing giants Charlie Munger and Warren Buffett. For a CEO who desperately needs to raise capital, Musk sure is being rude to investors this week.