Worked as a carnival worker; or past tense of being deceived by carnival tricks.
From 'carnie' as a verb, adding the regular past tense '-ed' suffix. This represents the verbification of a noun that became common in 20th-century American English.
When a noun becomes a verb, it often indicates something culturally significant enough that people need to make it an action—saying 'I carnied one summer' captures an entire lifestyle and set of experiences in one word.
Complete word intelligence in one call. Free tier — 50 lookups/day.