I'd have joined in the conversation, since its volume indicates it was open to anyone.

"What do you mean that's Bulls***? I'm buying one *million* shares. Have you seen the reports and financials? Does the CEO know what you're up to???"

And so on. I would have made it impossible for him to get any words in without having to try to tune out me and my participation in his loud conversation. Eventually, a truce would be declared, I guarantee it.