Mountain Dew is a soft drink and not an actual mountain, but there are jokes. A popular “yo mama” insult “stupid joke” is:
 
“Yo mama is so stupid, she tried to climb Mountain Dew.”
   
The joke has been cited in print since at least 2007 and has been printed on many images.
 
       
Wikipedia: Mountain Dew
Mountain Dew (stylized as Mtn Dew) is a carbonated soft drink brand produced and owned by PepsiCo. The original formula was invented in 1940 by Tennessee beverage bottlers Barney and Ally Hartman. A revised formula was created by Bill Bridgforth in 1958. The rights to this formula were obtained by the Tip Corporation of Marion, Virginia. William H. “Bill” Jones of the Tip corporation further refined the formula, launching that version of Mountain Dew in 1961. In August 1964, the Mountain Dew brand and production rights were acquired from Tip by the Pepsi-Cola company, at which point distribution expanded more widely across the United States and Canada.
       
Squackle.com
“You’re So Stupid” Insults
Posted on September 15, 2007 by LouBoy
These can also double as “Your mom is so stupid that…” or “Your mom is so stupid…” or “I knew a Blonde so stupid that…” or “You’re so dumb that…” or “Your mom so dumb that…” or “Your mamma/momma so stupid that…”
(...)
…you tried to climb Mountain Dew.
 
Twitter
come on eileen
@EileenBertot
Gisselle so stupid, she tried to climb mountain dew
4:06 AM - 17 Jul 2009
   
Twitter
@DuRagModel
@highclasscoon
#YOMAMA so stupid, she tried to climb “Mountain Dew”
7:40 PM - 30 Oct 2010
   
Twitter
NerdJohnson
@Luis_Skullnick
yo momma so dumb she tried to climb mountain dew # momjokes
6:54 PM - 8 Nov 2010
       
YouTube
YO MAMA SO STUPID! Mountain Dew
Yo Mama
Published on Aug 28, 2011
 
Google Books
Crazy Zubb’s Joke Book
By Joey Williams
Lulu Press (Lulu.com)
2014
Pg. ?:
Yo mama so dumb she tried to climb Mountain Dew.
 
Reddit—Jokes
Your momma so dumb
submitted April 25, 2014 by Brewfall
she tried to climb Mountain Dew
     
Google Books
Yo Momma So Stupid Jokes 2
By Peter Crumpton
PeteyRF Creative
2015
Pg. ?:
YO MAMA IS SO STUPID!
she tried to climb Mountain Dew.
 
Reddit—Jokes
Yo Momma so dumb
submitted April 15, 2015 by X-3
she tried to climb mountain dew and thinks Fleetwood Mac is a new hamburger at Hardees.
     
YouTube
Jokes - Yo momma is so stupid she tried to climb Mountain Dew.
jokesus
Published on Aug 11, 2015
Joke :
Yo momma is so stupid she tried to climb Mountain Dew.
 
Reddit—FunnyYoMamaJokes
Yo Mama so dumb, she tried to climb mountain dew (self.FunnyYoMamaJokes)
submitted September 3, 2015 by PragyaG
Hahaha… :D
 
Twitter
🙊A to Z, What Could It Be 🙊™
@TangledHotMess
Yo mama so dumb she tried to climb mountain dew
#TellAYoMamaJoke
3:17 AM - 23 Apr 2018
     
Reddit—Combined Gifs
Yo mama so stupid she tried to climb mountain dew. (i.redd.it)
submitted May 18, 2018 by NoTrophys4me