snake oil

Short definition from Wiktionary

Noun

1. 1
   A fraudulent, ineffective potion or nostrum; panacea.
2. 2
   A traditional Chinese medicine used to treat joint pain.
3. 3
   A type of 19th-century patent medicine sold in the United States that claimed to contain snake fat, supposedly a Native American remedy for various ailments.
4. 4
   Any product with exaggerated marketing but questionable or unverifiable quality.

Verb

1. 1
   To dupe or con.