OEandricearoni
Bluelighter
^^^^ No one smokes actual formaldehyde. Formaldehyde is highly carcinogenic and will kill you if you ingest more than a few parts per million. Formaldehyde is a common nickname for PCP, and this article probably just got it mixed up.
I know that it's a common name for PCP but It's pretty well documented that some morons have smoked actual embalming fluid with weed.
http://neuro.psychiatryonline.org/cgi/reprint/6/1/67b.pdf
It's dumb as hell and dangerous, but some idiots have done it apparently.