"Derrière” sounds like “dairy air.” A milk joke was posted on Reddit—Puns on August 23, 2017:

Q: What does a fart from a hard-core milk drinker smell like?
A: Dairy-air.

A haiku using “dairy-air” was posted on the newsgroup alt.arts.poetry.comments on June 22, 1999. “Dairy air” was entered in the Urban Dictionary on August 29, 2010, and the term has been printed on several images.


Google Groups: alt.arts.poetry.comments
Haiku ~ HUSH MIST Repost
News
6/22/99
(...)
Hush! Missed a cow fart
slicker’s stinky-ass wind-chime
is hick’s dairy-air

Twitter
Ceryk‏
@Ceryk
@NathanFillion Dairy Air? Like, what, milk burps and cheese farts?
4:55 PM - 26 Mar 2010

Twitter
Rob Deez‏
@robdeez
I wonder if the word #derriere got it’s name from people drinking #milk & then #farting. #dairy #air
8:58 AM - 25 Aug 2010

Urban Dictionary
dairy air
Common misspelling of the French word derrière which refers to the buttocks.
Don’t be hating because my derrière (dairy air) is bigger than yours.
#dairy air#butt#buttocks#buttock#ass#booty#rump#derrière
by krazykid933 August 29, 2010

Twitter
JULIET TRAPULET.‏
@DoItTheRightRAE
@StarburstNycol Niggas lookin at her eggs, her cheese & her milk! “Lookin at my dairy-air.” lolol *dérriere
11:49 AM - 26 Dec 2010

Twitter
Eugene the Space Cow‏
@EugeneTSpaceCow
Does excessive methane release (farting) ruin a cow’s milk production? Yes, because of the poisonous dairy-air.
12:29 AM - 16 Mar 2011

Twitter
Nils Parker‏
@NilsAParker
Has anyone ever made the joke that milk farts are just dairy air? If not, COPYRIGHT! Effective immediately.
4:17 PM - 4 Mar 2012

Twitter
juan the baptiste‏
@Thefunny_Juan
What do you call a lactose intolerant ass?... A Dairy Air lol get it cuz wen they fart its like spoiled milk lmfao
7:58 PM - 20 Mar 2012

Twitter
Maddie Martinez‏
@fakemaddie
What do you call your farts after you drink milk?
Dairy-air™
3:25 PM - 28 Apr 2017

Reddit—Puns
What does a fart from a hard-core milk drinker smell like? (self.puns)
submitted August 23, 2017 by massivebrain
Dairy-air

Twitter
Patti Rowlson‏
@PattiRowlson
Smells like “dairy-air” round here. @stacee #farmtour #ag #business
4:59 PM - 24 Aug 2017