Pepper dust is a ubiquitous byproduct of the spice trade. We grind a lot of pepper and that produces a lot of dust. It is nasty stuff and not that useful.
This is an ideal gag gift for those who may be on your naughty list. It is the spice version of the old lump of coal. Pepper dust is somewhat useful if you need an ultra-fine pepper or if you need to induce sneezing.