HaHaHa!! Wog Day? If you're in the USN (or USMC and be TDY on a Navy ship) and CROSS THE EQUATOR, you have to be, ahem...."inducted", shall we say, from the ranks of the Slimy Polywogs (non-crossers) into the ranks of the Trusty Shellbacks (crossers). Lotsa time spent on your hands and knees, for openers---
I'm not supposed to say much about it, not even sure if it's still allowed anymore in these PC days (does anyone know?). I believe it started in the Royal Navy many moons ago, and the tradition carried over into the USN. An official entry was made in your Bupers (personnel) file when you became a Trusty Shellback, so if you were still a Slimy Polywog when you crossed the equator, the command already knew about it, and there was no escape.
Somewhat unpleasant at times, but generally a lot of fun.