When describing the units, the correct plural is stones (as in "Please enter your weight in stones and pounds").

When he asked me the correct plural, I told him octopoda.

"3Gs" is the correct plural of "3G."

The correct Greek plural is proboscides, but in English it is more common to simply add -es, forming proboscises.

"Two twonkies," I said, wondering if that was the correct plural.

It's the correct plural of octopus.

The correct plural is supernovae, Doctor.

Recognizing postpositive adjectives in English is important for determining the correct plural for a compound expression.

The sheer popularity of the octopus here has even provoked a debate over the correct plural for the sea creature.

"Actually, the correct plural is octopodes, even though everyone now accepts octopi because it has been used so much."