This post caught my attention because the poem is briefly quoted in the 80's movieDead Poet's Societythat stars Robin Williams. The teacher that Williams plays in the show tells the boys that the poem is about Carpe Diem!-- or seize the day! This later inspires the boys to experiment in a variety of activities that their parents probably wouldn't appreciate.
The poem is satirical. The speaker is basically trying to get the girls to give in to him. He tells them they won’t be young and beautiful, so what are they waiting for?