a rumpus of baboons Fanciful / unverified Subjectbaboon (baboons)CategoryAnimals → MammalsConfidencelowAttestationwiktionary-wordlist-only 2 sourcesWiktionary - rumpusWiktionary - Appendix:English collective nouns
a rumpus of phantoms JokeFanciful / unverifiedModern coinage Subjectphantom (phantoms)CategorySupernatural → Ghosts & spiritsConfidencelowAttestationhumor-source 1 sourceWondermark #566 - Supernatural Collective Nouns (David Malki !, 2009)