Meaning: Here, 'rifle up' is an extreme alternative to 'pop up'. Also, there is little to no possibility that the nose of a woman broke with a piece of toast. This is a fine example of hyperbole being used to add humor to a statement.
Meaning: Here, we know that China and Africa can never meet and that oceans will never be hung to dry. These ideas are impossible. The poet has implied this 'impossibility' as the depth of his love. Here, hyperbole is used as a rhetorical device.