Larry Ellison doesn't much care if you know he sleeps with employees, fabricates advertisements, or taunts people with his wealth. But what the Oracle CEO doesn't want you to hear is a presentation from a guy he invests in and who worked for him for 13 years. Especially if Ellison has the power to cancel that guy's speaking gig, humiliating him in the process.

Marc Benioff, CEO of Salesforce.com, was slated to speak at Oracle's OpenWorld conference today. But it seems OpenWorld isn't so open: Benioff's gig was apparently cancelled at the last minute, prompting Benioff to issue an angry tweet and pundits to accuse Ellison of melodramatically drop kicking a competitor, professional wrestler style. Ellison picked an odd nemesis: Ellison was a seed investor in Benioff's company, named him "rookie of the year" at Oracle, and licenses his software to the guy. But he also covets Salesforce's customers. So — whoops! — looks like Benioff's long scheduled presentation at Ellison's conference couldn't be accommodated, after all.

Oracle did offer Benioff a slot on Thursday morning — the last day of the conference, when no other speaker sessions are planned. Burn.

[Photos of Ellison and Benioff (inset) via Getty Images]