In which I discover why my hands are sticky

Before lunch the other day, I washed my hands before taking the students down to the cafeteria. We got through the lunch line and settled down at the table. I was circulating around the table, monitoring the class, and halfway through lunch, I noticed that my hands were really sticky. It seemed odd to me, since I wasn't eating anything sticky. Hmm...

I washed my hands and went back to lunch. From across the cafeteria, I observed Sandy relaxedly drawing a line of jelly taken from her sandwich, onto my Snapple bottle (she's a very tactile child). Ohhhhhkay. Right-o. "Hey, Sandy...."