Want to steal someone's idea that you really wish you'd though of ?
Simple. Right now, create an idea called, for example, "Prior art placeholder". Put some bland, uninteresting filler text in the idea body (just cut and paste it from one of [beany]'s ramblings).
When an idea is posted that you
wish you'd thought of, perhaps years later, simply edit your "placeholder" idea to closely resemble it, delete any inappropriate annotations, then link across from the "new" idea claiming "Prior Art !" in an offended tone and marking it for deletion.
The date of your idea will automatically pre-date the "new" version (since origination dates don't change even if the idea is massively edited), thus the unfortunate author will be pilloried for, at worst, failing to search, and at best blatant plagiarism.
Of course, this idea is dishonest, petty, unworthy, and totally contrary to the spirit and ethos of the HB.
We're amazed it hasn't been thought of before ...