The kylix was a shallow drinking vessel with a stem and base that was commonly used throughout the symposium experience. Foremost it was used as a vessel, in which wine was drunk from the shared krater. However, beyond just as an alcohol receptacle, it could provide a large number of other types of entertainment. Decoration at the bottom of the bowl of the kylix was revealed as the symposiast drink. This art could be anything from scenes of mythology to lewd depictions of erotic acts. Similarly the bottomside of the kylix, which attached to the stem was also frequently decoracted. The shallow nature of the kylix meant that in order to drain alcohol from the bowl, it had to be tipped nearly vertically. This resulted in the paintings on the bottom of a kylix being revealed. Particularly humerous were eye-cups. These kylikes had two large eyes painted on their bottoms, which (when the cup was being drained) acted almost like an exaggerated mask for the symposiast drinking. These seemingly simple entertainments were made all the funnier by the intoxication of all members of the symposium present.
Of course, it might seem easy to dismiss these entertainments and frivolous or strange to people in the modern day. However, even we have equivalents, such as these novelty "nose" cups. They serve much the same purpose and use comparable humor to ancient eye-cups, proving that in surprising ways we are similar to the ancient Greeks.