Why are eletric fields blue and magnetic ones green ?
I'm on the verge of graduating and still don't get it (never explained)

Sounds just like a color coding system to me.
Nothing to do with Electromagnetism as far as I know, and I've had three courses entirely on Electrostatics/Dynamics/Magnetism.

a professor drew it up on a white board and those were the two markers he had. been that way ever since.

because you touch yourself at night

Also convention doesn't usually have a good reason.....