The graph with two vertices and $n > 1$ edges connecting them has been called the "banana graph" in a number of papers. For one example, see "Feynman Motives of Banana Graphs" by Aluffi and Marcoli, *Comm. in Number Theory and Physics* (2009) 1-57. (The short title of this paper is "Banana Motives", which I find endlessly entertaining.)

Does anyone know who coined the term "banana graph"?