New York City is the “Big Apple,” and Lagos, Nigeria (the most populous city in Africa) has been called the “Big Yam.” Yam is a popular African food. “Lagos: The Big Yam” was the title of an article in The Economist on March 14, 2009. “Fun fact. Lagos is called the big Yam now, like NY is the big apple” was cited on Twitter on August 1, 2016.
 
Lagos has also been called “Africa’s Big Apple” and “Big Agbalumo.”
     
   
Wikipedia: Lagos
Lagos /ˈleɪɡɒs/ (Yoruba: Èkó) is a city in the Nigerian state of Lagos. The city, with its adjoining conurbation, is the largest in Nigeria, as well as on the African continent. It is one of the fastest growing cities in the world and also one of the most populous urban agglomerations in the world. Lagos is a major financial centre in Africa; the mega city has the highest GDP, and also houses one of the largest and busiest ports on the continent.
 
Google Books
The Economist
Volume 390, Issues 8618-8624
14 March 2009
Pg. 51:
Lagos
The Big Yam
SPEND an evening at the tree-lined Seaside Bar on Ikoyi Island and it is possible to come away with a rosy view of Lagos. Revellers clink bottles and gaze across shimmering water. A motor-cruiser festooned with twinkling lights swishes by, music booming. Spotlights illuminate a row of plush new waterside flats on neighbouring Victoria Island; cranes, radio masts and fast-rising hotels dot the skyline.
 
Daily reality is less alluring. Lagos has long suffered from overcrowding, jammed and broken roads, erratic supplies of power, violent crime, floods, filth and smog.
 
Twitter
MyVocal
‏@myvocal
Lagos. The Big Yam http://www.myvocal.com/catalog/items/4056504
12:02 PM - 16 Mar 2009
 
Twitter
a3
‏@Access2Adam
What’s it with PDP & Lagos? Now that we’ve separated them with the BIG YAM they’re hell bent on the SMALL YAM huh? My Lagos peeps never pls!
6:54 AM - 5 Apr 2015
 
Twitter
Ibrahim
‏@Ibrahim_says Ibrahim Retweeted Christian Purefoy
Lmao… Is Lagos the “big Yam” ??Ibrahim added,
Christian Purefoy @purefoyAMEBO
i dey kampe o! but d hustle is too much😀 i’m in lon-don at moment but will holla when i get back into the “Big Yam” @TunjiLardner how u dey?
5:46 AM - 27 Apr 2016
Republic of Mauritius
 
Twitter
Christian Purefoy
‏@purefoyAMEBO
Yup - America has the Big Apple, so lagos has the big Yam 😝 @Ibrahim_says @TunjiLardner
6:27 AM - 27 Apr 2016
 
Twitter
Ibrahim
‏@Ibrahim_says Ibrahim Retweeted Ayshah Elnafaty
Fun fact. Lagos is called the big Yam now, like NY is the big apple.. It’s a real thing, ask @purefoyAMEBOIbrahim added,
Ayshah Elnafaty @3yesharu
Oh c’mon farido! Yam?? Mother Yam? A house that has no yam has no food. https://twitter.com/Faridaa_ahmad/status/760273474460024832 …
8:22 PM - 1 Aug 2016
Abuja, Nigeria