In Europe and the United States, popcorn is particularly common in movie theaters. It is often served with (often imitation such as margarine) butter and salt. It is also sometimes flavored with sugar (especially in Asia), nutritional yeast or spices. In the United States it is sometimes served with sugar and vinegar.
Popcorn balls (popped kernels stuck together with a sugary "glue") were hugely popular around the turn of the 20th century, but their popularity has since waned. They are still served in some places as a traditional Halloween treat. Cracker Jack is a popular, commercially produced candy that consists of peanuts mixed in with caramel-covered popcorn. Kettle corn is a variation of normal corn, cooked with white sugar in a large copper kettle. Once reserved for specialty shops and county fairs, kettle corn has recently become a popular variety in the microwave popcorn market.
Sam: FUCK!!! GODDAMMIT JOHN! WHY'D YOU HAVE TO POPCORN ME!?!?! I HATE READING OUT LOUD