It seems that Munich loves to snack, and a tempting array of food is available almost anytime. The generic term for a snack is Imbiss, and thanks to growing internationalism you'll find all types of them, from the generic Wiener (hot dogs) to the Turkish Döner Kebab sandwich (pressed and roasted lamb, beef, or chicken). Almost all butcher shops and bakeries offer some sort of Brotzeit snack, which can range from a modest sandwich to a steaming plate of goulash with potatoes and salad.
Some edibles come with social etiquette attached. The Weisswurst, a tender minced-veal sausage—made fresh daily, steamed, and served with sweet mustard and a crisp roll or a pretzel—is a Munich institution, and is served before noon with a Weissbier (wheat beer), supposedly to counteract the effects of a hangover. Legend has it that this white sausage was invented in 1857 by a butcher who had a hangover and mixed the wrong ingredients. A plaque on a wall on Marienplatz marks where the "mistake" was made. Some people use a knife and fork to remove the edible part from the skin; the rougher crowd might indulge in auszuzeln, sucking the sausage out of the Weisswurst.
Another favorite Bavarian specialty is Leberkäs—literally "liver cheese," although neither liver nor cheese is among its ingredients. It's a sort of meat loaf baked to a crusty turn each morning and served in succulent slabs throughout the day. A Leberkäs Semmel—a wedge of the meat loaf between two halves of a crispy bread roll slathered with a slightly spicy mustard—is the favorite Munich on-the-go snack. For late-night snacks go to the Schrannenhalle next to the Viktualienmarkt.