If nothing else, the water boatman sure knows how to cut to the chase:

The monsieurs boatman make their song by rubbing their right paramere's pars stridens (a grasping organ used for mating) against the eighth segment in their abdomen. This romantic instrument does not seem to be magnified by any internal resonating organs, so biologists and engineers are puzzling over just how this tiny guy manages to make such big noise. Even smaller is the contact area between the pars stridens and abdomen section, which is about 50 micrometers wide. "We really don't know how they make such a loud sound using such a small area," Windmill says.