Pour sugar syrup into a wide, flat container. Coarsely grind the pistachios and sprinkle them on a plate. Sprinkle chocolate shavings onto a plate as well. Dip glass edges (1-2 mm) in syrup.
Then dip 2 glasses in pistachios and 2 in chocolate shavings. Wrap ice cubes in a tea towel and crush them with a flat, heavy object. Mix the eggnog and crushed ice in the mixing bowl. Add lemonade, mix again, pour into the prepared glasses and serve