Chocolate ants are little black sprinkles made of out chocolate. They're called "ants" because they really do look like little, legless ants when you look at them. They're great on ice cream and cupcakes (as are most sprinkles in general.)
When I was a kid, I actually believed that chocolate ants were chocolate-covered ants. That's what my parents told me. They made up an elaborate story that the ants were forced to march into a vat of boiling, liquid chocolate. The chocolate was so hot, the legs got burnt off. I never thought to question how they were able to force ants to do anything because I believed everything my parents told me. Apparently they thought it was funny to mislead me and make me look like a fool when I told my entire second grade class that "chocolate ants" were real ants.
I never made the mistake of trusting my parents after that :)