A straw is fundamentally a singular hole. See Doughnuts; see also Bagels (a similar form to a doughnut and while sometimes fused at the center, the comparison is apt); Cf. human body (described as a doughnut, or to be more precise in topological terminology, a torus and though more ‘holes’ are colloquially attributed to the body there is but one interconnected path through). There are clearly not two holes in a doughnut. The same is true of the humble straw.

This brings us to the other utilization of the word “hole” which is to denote an emptiness of space. Louis Sachar, Holes (Farrar, Straus and Giroux 1998). This spatial definition of emptiness is a break in the expectations of a zone. Instead of dirt there is air. We would not say that an empty but unbroken styrofoam cup possesses a hole. However, should we take that cup and poke through the material, we have created an emptiness. Consider also the sock which has one opening. When one has a hole in the sock, it is an unanticipated break in the material through which a toe may poke. We put feet into the openings, or the top of the sock, not a hole.

We poke holes, we dig holes, we make an emptiness.

The straw is a mass of material bits surrounding an empty space, the hole. Some have argued that the numerosity of the straw’s holes are determined by plugging either side. They are merely counting the ends of one hole. Furthermore, if an end is plugged, the same emptiness nonetheless persists in the space between and the singular hole still remains by the definition in Sachar’s seminal text. Id.

The final conception of a hole is that of an out. A through-way for things or persons to pass between some barrier. A hole that connects two spaces is clearly used in the singular. Furthermore that is in accord with the historical utilization. The Beatles: Yellow Submarine, 1968.

However you describe the emptiness within the bounds of the toroidal arrangement of plastic or paper, it is but one hole.