From Latin, so this should technically be platypi, but now that we all know that well, actually octopus is from Greek and so ought to be octopodes, here we go. (The OED lists possible plurals as platypuses, platypi, (rare) platypusses, (rare) platypodes.)
datums, datopodes, dasta, data’s:
foxen, et al:
Taking the unusual Germanic -en option.
snooze/snost, lose/lost, house/hice:
Getting some verb tenses in there with the plurals.
wing, wang, wung:
Appropriate choices given how much he sings, sang, and has sung.