Obvious and intentional exaggeration or an extravagant statement or figure of speech not intended to be taken literal.
What effect does this rhetorical technique create?
Humor and exaggeration can both be effects that this rhetorical technique creates. In the examples above, they are exaggerating because it doesn't really mean they have been reading that book for a hundred years or that they could eat a horse. Humor is also used in the examples above because reading one book for a hundred years or eating a horse because you are so hungry is not realistic or practical.