None. Colloquially, we use "hole" in all kinds of weird ways. As others have pointed out, topologically a straw is no different to a torus (donut) that clearly has one "hole"... but I'd like to focus instead on the linguistic definition of "hole", not the colloquial or mathematic definitions.

A hole can either mean:

1. a perforation ("a hole in my shirt", "a bullet hole", etc) - which is, specifically, "a hole or pattern made by or as if by piercing or boring"
2. a gap ("a hole in your reasoning", "a hole in my heart", etc)
3. a hollowed out or burrowed place ("a hole in the road", "a fox hole", etc)

i think we're not talking about 2. It seems to require some larger uniform structure or set of items in which an item is missing. 1 and 3 seem really similar to me: both seem to require some active removal of matter to qualify. All of these definitions point towards a subtractive process, where something of a larger whole (heh) is removed or absent.

Most straws, I'll venture a guess, are not manufactured solid and then bored out.. so I don't think it applies here. So I don't think a straw matches a fitting definition of "hole". A straw is created additively by assembling the "shell" by some means, not subtractively. Donuts, by comparison, had holes punched in them. A subtractive operation. Rubber bands have not had holes punched in them... they're additive. Not holes.

Similarly (because I see a lot of talk about buttholes and mouths here too), your esophagus and digestive tract (and veins and all kinds of other things) were formed in a similar additive manner, not by forming a mass of meat and boring through the passage, and thus would similarly not qualify as "holes" (in my opinion).