Age and widespread ridicule have evidently not tempered Microsoft chief executive Steve Ballmer's crazy on-stage antics, with tech heads now getting a good laugh out of Ballmer's dummy spit at an iPhone-toting employee.

Late last week Microsoft held an all-hands company event in Seattle, which was called to discuss new products such as the Bing search engine, Windows 7 and the Xbox motion sensing app, dubbed Project Natal.

But after Ballmer bounded on stage with his usual skipping, shouting, hand-slapping buffoonery, he noticed an employee was trying to take a picture of him using his iPhone.

According to staff members' tweets and Facebook posts, and a follow-up report by the Seattle-based Techflash blog, Ballmer snatched the forbidden Apple device and pretended to stomp on it.

He also aimed some disparaging remarks at the Apple device - which were met by boos and jeers from Microsoft's staff members - and continued to refer to the incident later in his presentation, making sure the employee knew that he hadn't forgotten it.

Unlike some of Ballmer's other antics, the incident doesn't appear to have been captured on camera, although a clip of his over-the-top entrance at the event has been uploaded to YouTube.

Furthermore, Engadget has published a photograph that it claims was snapped by the offending iPhone just as Ballmer was snatching it.

As a Microsoft employee noted on Twitter: "You just don't pick up the CEO of Chevy in a BMW."

But despite the iPhone being taboo at Microsoft, a spokesman told The Wall Street Journal's Digits blog that the company had not made an effort to seek out the iPhone user and punish him for his breach of common sense.

The iPhone incident is just one in a long line of examples of raving, sweaty behaviour by the emotionally charged chief executive.

Examples range from the Ballmer shout-fest that was his ad for Microsoft's first version of Windows, to his trademark "monkey dance" and his chant of "developers, developers, developers".

He even popped out of a cake at Microsoft's 25th-anniversary celebrations.

Ballmer reserves particular disdain for arch-rival Apple's products, once saying the most common format on Apple's iPod was "stolen".

When the iPhone was launched, Ballmer laughed it off, saying it was "the most expensive phone in the world and it doesn't appeal to business customers because it doesn't have a keyboard".

In July, this website showed senior organisational psychologist Dr Peter Langford some video clips of Ballmer's behaviour.

Langford concluded that Ballmer was most likely not insane, saying instead that the cheerleading behaviour was deliberate.

Langford said at the time: "He's building a celebrity status for himself and Microsoft. It is important that CEOs are larger-than-life and this is his way of doing that."

- Sydney Morning Herald