I wouldn't call any extinction event a favorite, because it is a loss. An interesting one that is less known than the Dodo is that the wake island rail bird was hunted to extinction by starving Japanese soldiers in WWII. The Americans blockaded the island, trapping the Japanese there, and they ate all the birds in just a couple years time.
I think it's an interesting extinction because it's an unintended casualty of war.
This is the one where the ocean turned purple wasnt it?
Sounds right. I saw a documentary about it a fee months ago.