We all know people who are routinely late. We may even be one of them. These people aren't necessarily late for everything. They usually manage to catch their trains or planes, get to a concert before it begins, and make it to their job interviews on time. But if it's a matter of rendezvousing for coffee, not holding up dinner, or being packed for a trip by the prearranged departure time, they are systematically hopeless.
Surprisingly, English doesn't seem to have a noun for this kind of person akin to words like “slob” or “scruff” or “lazybones.” The term “latecomer” won't do since it denotes one who is late for a specific event, not one who regularly keeps other waiting. So for the sake of convenience, let's label these people “unpunctuals.”
On several occasions I have heard amusing little speeches given about such individuals, at birthday parties, anniversaries, and graduation celebrations. The spirit is always the same: the subject of the toast/roast is a lovely person in many, many ways but he/she has a unique (although, in truth, it obviously isn't unique) sense of time. A familiar consequence of this has been that the unpunctual's nearest and dearest have spent a goodly proportion of their earthly existence hanging around wondering when the unpunctual will show up/be ready/finish a task etc..
This charitableness toward the unpunctual is interesting. We are less ready to laugh at other little failings which inconvenience us. Imagine a similar speech about someone who regularly borrows money and doesn't pay it back. Or who routinely fails to pick up their share of the tab at a restaurant. Or who insists on inflicting loud music on us when we are trying to concentrate or are suffering from a migraine. In such cases, the humour would be more barbed, the implicit criticism more pointed.