On Vesak Day, Buddhists all over the world commemorate events of significance to Buddhists of all traditions: The birth, enlightenment and the passing away of Gautama Buddha. As Buddhism spread from India it was assimilated into many foreign cultures, and consequently Vesak is celebrated in many different ways all over the world.
Actually the name 'Wesak' or Vesak is only in use in Sri Lanka and in Malaysia, it's known by lots of other local names across Asia. I'm not a Buddhist, but as you know, Malaysia is a multi-cultural country that embraces different traditions.
Most Buddhists i know go vegetarian for the day, and spend the morning in the temple.
Incidentally, this year, Wesak falls on Labour Day, too.