The player controls Mighty Mouth, displayed on screen as a pair of disembodied lips that appear similar to a Chattery Teeth toy. Various fast food items fly across the screen and the player earns points by catching them with Mighty Mouth.
However, Mighty Mouth must avoid eating purple pickles. If Mighty Mouth eats six purple pickles, the screen clears and "BURP" is displayed in large letters, followed by "CLOSED".
As the player acquires more points, the speed of the game increases. The transitions between speeds are indicated by the message "YOU'RE GETTING FATTER!"
Source: Wikipedia, "Fast Food (video game)", available under the CC-BY-SA License.