jboponei is the practice of replacing all abstraction cmavo (of class NU) with the word po, terminated by nei. (Note that these replace existing cmavo, meaning ‘exclusive possession’ and ‘this bridi relation’.)
At first, Lojban was replete with abstractor usage – jbopre were eager to nu and ka and du'u and za'i and ni and zu'o… However, a subset of them [TODO: who, when?] settled on a peculiar habit: in place of all of them, using the su'u abstractor (the most general and inspecific of them all). Then lo su'u got shortened to po. This modification caught on, almost virally (ironically since it’s 2020), and as such has ended up as part of most active Lojbanists’ dialects.