“Don’t put sugar on shit and tell me it’s a brownie”

To “sugarcoat” something is to make something more pleasant than it actually is. “Don’t put/sprinkle sugar on shit and tell me it’s a brownie/candy/chocolate” is a stronger way of saying not to sugarcoat something.
 
“Don’t sprinkle sugar on shit and tell me it’s fucking candy!” was cited in 2006. “Don’t put a turd in front of my face and tell me it’s a brownie” was cited in 2008. “You can’t sprinkle sugar on shit and tell me it’s chocolate” was cited on Twitter on October 13, 2009.
   
“Don’t put sugar on shit and tell me it’s ice cream” is a related saying. “Don’t feed me manure and tell me it’s ice cream” and “Don’t pee on my leg and tell me it’s raining” are similar sayings.
     
 
The Free Dictionary
sug·ar·coat  (sho͝og′ər-kōt′)
tr.v. sug·ar·coat·ed, sug·ar·coat·ing, sug·ar·coats
1. To cause to seem more appealing or pleasant: a sentimental treatment that sugarcoats a harsh reality.
2. To coat with sugar: sugarcoat a pill.
 
YouTube
WHOA
Don’t sprinkle sugar on shit and tell me it’s fucking candy! 5 videos No views Last updated on Aug 28, 2006
   
Iowa Sportsman
Piss and Moan  
Heinrix_54
February 15 2008 02:56PM
not in a bad mood…..............i’m done with the subject but don’t put a turd in front of my face and tell me it’s a brownie…......cause it sure as heck still smells like a turd
     
Twitter
SUPER DOPE!
‏@TA_SUPER_DOPE
You can’t sprinkle sugar on shit and tell me it’s chocolate…..chocolate can make you shit though!
11:29 AM - 13 Oct 2009
 
Primos Cabin Chat
Elk Hunting
Elkhunttoo 
post Jul 26 2010, 02:48 AM
(...)
Not tying to be rude, but don’t poop in the snow and tell me it’s a brownie.
 
Twitter
bigDADDY midgetDICK
‏@Smartazz_
Dont put sugar on a piece of shit and tell me its a candy bar…its a piece of shit. Dont sugar coat what you wanna say either. JUST SAY IT!
9:27 PM - 26 Aug 2010
 
Twitter
Inspector Ratchet
‏@DrunkenNo_Odle
Don’t sprinkle sugar on your bullshit and then tell me it’s candy!
3:01 PM - 7 Dec 2010
 
Twitter
Martell Williams
‏@HoldOn_Shawty
Dnt put sugar on s**t and tell me its chocolate!
8:55 AM - 31 Jan 2011
 
Twitter
tassja arielle
‏@tass_boogie
don’t poop on my plate and tell me it’s a brownie.
7:50 AM - 19 Feb 2011
 
Twitter
Blak Sou£
‏@Mic_Mack
Dont put sugar on shit and tell me its cake
5:58 AM - 18 Jan 2012
 
Twitter
Bassem Reda
‏@bassem415
Don’t put sugar on shit and tell me it’s a brownie !!
1:52 AM - 8 Feb 2013
 
Twitter
FreakO
‏@PUFFtvFreakO
Don’t try to sugar coat shit and tell me it’s a Brownie….
7:53 PM - 20 Jun 2013
 
Twitter
Trevor Keveloh
‏@TrevorKeveloh
@Meagabux don’t sprinkle sugar on dog shit and tell me it’s a brownie.
9:50 AM - 2 Dec 2013
 
Twitter
Niko Z
‏@DJRawDaddy
If you’re going to give me shit don’t sprinkle sugar on it and tell me it’s a brownie.
11:32 AM - 23 Mar 2014
 
WDSU News (New Orleans, LA)
Andrew Jackson statue comes under scrutiny at City Council meeting
Published 5:20 PM CDT Mar 31, 2016
(...)
Councilwoman Stacy Head replied, saying, “Much of what you say resonates with me because I detest inconsistency. I would prefer, to use an old adage, ‘If you’re going to feed me horse poop, tell me it’s horse poop. Don’t sprinkle sugar on it and tell me it’s a brownie.’”