The title, "Having a Coke with You," does a lot of jobs in this poem. In its most simple terms, it tells us what the poem is going to be about. It sets the scene: speaker + you + Coke = poem. Got it? Good. So we have an established backdrop of activity right from the get-go, and we understand what's going on before we dive into the poem any deeper.
Of course, there's more to it than that (there always is, isn't there?). The title is also the first line of the poem. This is not an unheard-of strategy in poetry, where the first line of the poem actually serves as boththe opening line and the actual title. So what's the effect of that kind of first-line-and-title double duty?
Well, one undeniable effect is that of speed. Clearly, the title is not repeated in the poem. We simply launch right into the poem from the title. The title then acts as a kind of catapult, propelling us as readers headlong into the text. At the same time, O'Hara is propelling us right into this conversation, and the speed with which the title does this gives us a sense of energy, and urgency, to what's being discussed here. This isn't somebody talking about his favorite wallpaper. He's got something urgent to tell you. So listen up, Shmoopers.