“All-purpose flour” (also called “AP flour”) can be used for baking many things, although professional bakers usually use other flours. “Purpose” should not be confused with “porpoise,” but there are jokes.
   
“A joke I just made up: What does a dolphin bake with?...‘All Porpoise Flour’” was posted on Twitter by Shawn D on August 7, 2020. “What does a dolphin bake with? All porpoise flour” was posted on Twitter by Erich Guebert on August 17, 2015. “What type of flour do dolphins use when baking? All Porpoise Flour!” was posted on Twitter by Steve Endow on March 3, 2019.
       
“Thought I could put dolphin in my fish pie. Until I noticed I was using all porpoise flour” was posted on Reddit—Jokes on September 19, 2015. “Thought I could put dolphin in my fish pie. Until I noticed I was using all porpoise flour” was re-posted on Reddit—3amjokes on December 22, 2020.
 
“All Porpoise flour is NOT dolphin safe” was posted on Twitter by Frankincense & Mers, Attorneys at Law on March 4, 2019. A dolphin-safe label is usually used for tuna.
       
“All-purpose flour has a limited number of uses” and “You cannot use all-purpose flour for all purposes” are “all-purpose flour” sayings.
     
         
Wikipedia: Flour
Plain or all-purpose flour
All-purpose, or “AP flour”, or plain flour is medium in gluten protein content at 9.5-11.5% (10-12% from second source) protein content. It has adequate protein content for many bread and pizza bases, though bread flour and special 00 grade Italian flour are often preferred for these purposes, respectively, especially by artisan bakers. Some biscuits are also prepared using this type of flour. “Plain” refers not only to AP flour’s middling gluten content but also to its lack of any added leavening agent (as in self-rising flour).
     
Twitter
Shawn D
@shawnd
A joke I just made up: What does a dolphin bake with?...“All Porpoise Flour”
7:25 PM · Aug 7, 2010·Twitter for iPhone
 
Twitter
Daniel Crist
@Punny_Guy
All Porpoise Flour. It like flour but made for dolphins.
1:47 PM · Aug 29, 2012·Twitter for Android
   
Twitter
Chris Mintz
@dieselRuns
When a recipe asks for “all porpoise flour” and I’m nowhere near a fish market, what’s a good alternative? #QuestionsWhileBakingCookies
12:03 PM · Dec 9, 2012·TweetCaster for Android
   
Twitter
Aaron Fraser
@ChefAaronFraser
I think there’s something fishy about this all porpoise flour.
5:01 PM · Mar 15, 2013 from York, New Brunswick·Twitter for BlackBerry®
   
Twitter
John Paul Khoury,CCC
@chefjohnpaul
If I was going to bread a dolphin would I use All Porpoise flour?
10:54 PM · May 24, 2013·Twitter Web Client
   
Twitter
bloom massage
@bloommassage1
Replying to @blackbirdbread
@blackbirdbread sorry, here’s one for you
What did the dolphin use to make his bread?
All Porpoise flour
waka waka waka!
6:39 AM · May 23, 2014·Twitter Web Client
   
Twitter
Erich Guebert
@peter_danklage
What does a dolphin bake with? All porpoise flour
2:12 PM · Aug 17, 2015·Twitter for Android
     
Reddit—Jokes
Posted by u/candu2 September 19, 2015
Thought I could put dolphin in my fish pie.
Until I noticed I was using all porpoise flour.
 
Twitter
Philip A Gertzel
@PhilipGertzel
What does an orca use to make bread?
All porpoise Flour
GIF
11:30 AM · Jul 23, 2016·Twitter for iPhone
   
Twitter
kyle horn
@khornpowered
Did you know they use 100% ground up cute dolphin in all porpoise flour?
11:29 AM · Dec 5, 2017·Twitter for Android
     
Twitter
Mike Cecconi
@Cecconi140
If you’re not sure if your tuna is dolphin-safe or not, try combining it with some all - porpoise flour.
1:43 PM · Dec 27, 2017·Twitter Web Client
 
Reddit—Dadjokes
Posted by u/allpourpoiseflour October 12, 2018
What is a dolphins favourite baking ingredient?
All Porpoise Flour!
   
Twitter
Steve Endow
@steveendow
What type of flour do dolphins use when baking?
All Porpoise Flour!
#DadJoke
1:52 PM · Mar 3, 2019·Twitter for iPhone
   
Twitter
Frankincense & Mers, Attorneys at Law
@stevenmers
All Porpoise flour is NOT dolphin safe.
7:04 PM · Mar 4, 2019·Twitter for iPhone
   
Twitter
Andy Simmons
@GristleSteakham
I only use dolphin flour when baking. I use it because it’s all porpoise flour.
11:16 AM · Feb 14, 2020·Twitter for iPhone
   
Twitter
Grace Parkes
@GraceParkesFic
Replying to @ashleystorrie and @JaneyGodley
Thought I could put dolphin in my fish pie.
Until I noticed I was using all porpoise flour
5:45 PM · May 25, 2020·Twitter for iPhone
 
Reddit—3amjokes
Posted by u/kickypie December 22, 2020
Thought I could put dolphin in my fish pie.
Until I noticed I was using all porpoise flour.