May 31

Critical Mass Cyclists and other self-propelled riders cruise through city streets to promote non-polluting forms of transportation. Meet at Vancouver Art Gallery, May 31 (and last Friday of every month), 5-5:30 pm, free, velolove.bc.ca.
-- Playground listings in The Vancouver Sun, Thursday May 29 2008

Correction: May 30. I hope there weren't any riders showing up at VAG on Saturday the 31st because they would have been quite disappointed. At first I wondered if this was the Sun's subtle way of decreasing the number of participants in Critical Mass, but their bit in parenthesis is correct so probably not - unless they wanted less participants in that particular CM. Also, the ride doesn't get going until after 6. Therefore, unless you wanna hang out for a bit, showing up between 5:30pm and 6pm would be better than 5-5:30pm.