Or make it uncomfortable. Meetings of Queen Elizabeth with the UK's Privy Council are conducted standing up to prevent them from running too long, a custom that began in 1861. (During that dark time before the agile manifesto was signed and history was rebooted).

It takes advantage of a simple exploit: if the Monarch is standing, nobody present may sit down, unless they are bodily incapable of standing. Queen Victoria didn't like long meetings, so she stood up to ensure they would be brief.

Yes stand-up meetings are a great idea.

Surprisingly effective. :)