One of my favorite joke(?) cmavo is zu'i'o'e standing for any noun phrase (potentially quantified)
I came up with the zu'i + zi'o + zo'e but the meaning was suggested by someone else. (I need to check roljbogu’e for that)
.i je'u mi ralnei zo «poi'i» loi ciplanli cmavo .i ku'i mi nelci lonu mi basti zo voi zo poi'i .i zo poi'i mutce co vlipa zo'ei lo gerna .i sepi'o zo poi'i ka'e skuna lo poi'i cau py. ke'a na ka'e se skuna
My favorite experimental cmavo is «po'i». However, I like to replace «voi» with «poi'i». «poi'i» is very powerful grammarically. Using «poi'i», you can say thing you can't say without it.