As it is very perishable, weißwurst is traditionally eaten for breakfast (there is a saying that the sausages should not be allowed to hear the church bell's 12 o'clock chime). The sausages are heated in non-boiling water, then eaten without the casing. The traditional way of cutting open the sausage, then sucking out the meat is known as "zuzeln".
Weißwurst is commonly served with sweet mustard and accompanied by brezen and weissbier.
It should be noted that Weißwurst are generally unfamiliar in northern Germany - a fact that helped coin the term Weißwurstäquator.
Of course, first you should know what Weisswurst is. Weisswurst is a white sausage which is made of veal, pork and spice, which are all stuffed into animal intestines.
'Weisswurstmustard' is coloured brown with a slight touch of green and tastes very mild and a bit sweet as opposed to hot mustards which are of a yellowy-green colour and taste very spicy.
If you order Weisswurst, you normally don't have to worry about ordering the correct mustard, because it will be served automatically, or it will already be on the table.