Food
Butterbeer
Butterbeer is the sweet drink served at the Three Broomsticks in Hogsmeade and, later, in other wizarding gathering places. House-elves can get drunk on it. Harry tastes it on his first secret visit to the village, while he is hidden in a corner listening to teachers talk about Sirius Black.

In the books
Harry Potter and the Prisoner of AzkabanChapter: The Marauder's Map
Harry drinks Butterbeer in the Three Broomsticks during the Hogsmeade visit he makes with the Map.