That wasn’t very cash money of you refers to a meme, paired with a drawing of the character Sayaka Miki from the Puella Magi Madoka Magica franchise.
The expression is a variation on the phrase “that wasn’t very cool of you”.
“That wasn’t very cash money of you” was turned into an exploitable meme, with various characters depicted with sunglasses saying the phrase.
The original picture with the catchphrase was uploaded to Tumblr by user things-in-sunglasses on January 26th, 2014.
People replicating the image with various other characters, paired with the catchphrase and sunglasses, spread the format online.
“That wasn’t very cash money of you” would appear on Twitter, Deviant Art as well as Urban Dictionary in 2015.
Another version of the format started appearing on Reddit’s /dankmemes subreddit in 2018, pairing the quote with a picture of Godzilla.