My turn for a "what's that smell" thread - Orchards edition

Because it's driving me bonkers and is making it damn near impossible to keep my apartment cool at night - what the *hell* is that goddawful smell in the Orchards area? Usually happens at night but sometimes in the day. Almost always comes from the east. Smells like rancid seafood and sulfur to my nose.

In unrelated news, I can't wait to move at the end of my lease!