When a male was chewing or severing the Chinese fan-palm leaves to make a tent, or when males crawled upon the upper surface of a tent or were grooming themselves within a tent, a female would fly to the tent, stretch her wings, move her head slowly towards the male, and then sniff the male’s face and neck. Subsequently, the pair’s heads extended towards each other and the bats would lick one another. At this time, the male would make approaches to the female with his thumbs.
If you teach statistics and have a good lawyer, you might consider using this article in class. Figure 2 (not shown) doesn’t have a bat illustration, but it has a fine interpretation of the regression line slope: “Therefore each second of licking prolongs copulation by approximately 6 s.”
Reference: Tan M, Jones G, Zhu G, Ye J, Hong T, et al. 2009 Fellatio by Fruit Bats Prolongs Copulation Time. PLoS ONE 4(10): e7595.doi:10.1371/journal.pone.0007595