stunk like a mackerel

Verb

stink like a mackerel (third-person singular simple present stinks like a mackerel, present participle stinking like a mackerel, simple past stank like a mackerel, past participle stunk like a mackerel)

1. (simile) To reek; to smell terrible.
2. (figuratively, simile) To smell fishy, to stink to high heaven (to look extremely suspicious or unconvincing).
   • In summary, I think that the waterfront situation "stinks like a mackerel in the hot sunlight."1965, Fleet Owner - Volume 60, page 8

   Synonyms:

   stink like a mackerel in the moonlight, stink like a mackerel in the sun