Macy’s department store has been mentioned in a “yo mama” insult joke:
 
“Yo mama is so stupid that when she walks by the YMCA she says, ‘hey look, they spelled MACY’s wrong.’”
 
The joke has been cited in print since at least 1998.
 
 
Wikipedia: Macy’s
Macy’s, originally R. H. Macy & Co. (stylized as macy’s), is a mid-range chain of department stores owned by American corporation Macy’s, Inc. It is one of two divisions owned by the company, with the other being Bloomingdale’s. As of January 2014, the Macy’s division operates 789 department store locations in the continental United States, Hawaii, Puerto Rico, and Guam, including the prominent Herald Square flagship location in Midtown Manhattan, New York City.
   
Google Groups: rec.music.makers.guitar
Hey Yo Mama
Joe Bac
10/27/98
Thing’s sure have been quiet in this newsgroup this week.  I’m sure it’s welcome by all.  Including me.
 
But wotdahell, nuttin like a yo mama joke?  Yo mama is so stupid that when she walks by the YMCA she says, “hey look, they spelled MACY’s wrong”. 😊

Google Groups: rec.climbing
“Your Mother”
Spiral Climbing Company
1/21/99
(...)
YOUR MOTHER IS SO DUMB
THAT WHEN SHE WALKED BY THE Y.M.C.A., SHE SAID
“LOOK HONEY, THEY SPELLED “MACY’S” WRONG”.
 
Google Groups: alt.sports.football.pro.phila-eagles
717-426-1778
Glenn Wilkie
3/28/99
“Jokely’s Mamma’s So Fat”
(...)
your momma is so stupid she walked past the ymca and said look honey someone spelled macys wrong.
     
Google Groups: alt.tasteless.jokes
Yo momma
GP of ATJ
10/7/04
(...)
Yo momma’s so stupid she walked past the YMCA and said look, somebody spelled MACY’S wrong.
 
Twitter
Tel
‏@Tellyvision3
yo momma so dumb, she passed by the YMCA and said hey they spelled MACYs wrong
12:37 AM - 6 Jul 2009
 
Twitter
Sammy
‏@GymShortComedy
yo mama’s so dumb, she drove by macys and said, ‘’ haha look, they spelled ymca wrong’’ 😛
8:01 PM - 22 Jul 2009