Is there anything more treacherous (besides my ex-wife) than a sideways sloping surface covered in ice? Maybe a sideways sloping surface covered in ice with a strong crosswind blowing

Or slippery: how about a polished frozen puddle with a light dusting fresh fluffy snow. Just enough to mask that it is there.

Or getting hit from the side with a wave of frozen slush from a passing semi? Man, that stuff is HEAVY.

What are your most treacherous riding conditions?