horned toad isn't a toad, but this is really a frog that really has horns, and it knows how to use them. Those nasty spines which are as sharp as a pencil point grow during breeding season and the males use them to fight (and also to "try to stab you a bit when you pick them up" according to the scientist who studied them). The fights happen because the males are protecting their eggs - which the females just lay and go back to the forests where they live the rest of the time. Nice to see that sort of division of labor in a species once in a while, if you ask me.
You can see video of a fight and read more at this link.