To be/get Ashdraked means to lose all your fund by shorting Bitcoin. This term is being used since 2014/2015 when a trader who was using the nickname Lord Ashdrake, lost all his funds by shorting Bitcoin at the price of $300 per unit.
As many times before, Lord Ashdrake has places short orders, expecting Bitcoin to drop again, like many times in the past. This time however, it kept on rising up to almost $600 in a period of 2 months, which effectively wiped all of Ashdrakes funds and kicked him off the markets.