Title text: Sn = tin
Cueball hands another Cueball-like guy an apple calling it a Snapple. When the guy bites into it his teeth goes clink. Cueball tells him it is because he has infused the apple with tin.
The fourth panel is a silent wide shot, perhaps suggesting the joke was met with silence as a weak joke. As a meta joke, the final panel might jokingly suggest that the silence is because those unfamiliar with the table of elements don't get the joke.
The joke in this comic is pretty self-explanatory; especially given that the image text continues the trend in early xkcd comics of explaining the joke. Tin is a metallic element whose abbreviation on the periodic table is "Sn" (as the Latin word for tin is "stannum"). Thus, the apple is a "Sn-apple."
In reality, Snapple is a brand of tea and juice based beverages whose name is based on a carbonated apple juice they once produced ("snappy apple").
- [Above the frame:]
- This one is entirely James' fault.
- [Two Cueball-like guys are standing and talking.]
- Cueball: Here, take a bite of this Snapple.
- Guy: food!
- [Guy takes a bite.]
- Guy: Ow!
- Snapple and teeth: Clink
- Guy: What is this?
- [Cueball explains:]
- Cueball: It's an apple infused with tin.
- [The two guys continue to stand as if frozen.]
- [Above two silent guys the following text is written inside a black frame:]
- Those of you who know your periodic table should be laughing right about now.
- This is another early xkcd comic in which Cueball characters are drawn in some panels with faces.
- This is the seventeenth comic originally posted to LiveJournal. The previous was 17: What If. The next was 19: George Clinton.