Not my circus, not my monkeys means it’s ‘none of my business’. It can also be said in cases when advice is given but not taken, and the attempt to solve the problem has failed. By saying “Not my monkeys, not my circus” you are saying kind of “I told you so”.
“Not my circus, not my monkeys” is originally a Polish proverb “nie nie mój cyrk, moje małpy”.
Actually it is not an old proverb as it is noted by Henryk Markiewicz and Andrzej Romanowski in Skrzydlate słowa: wielki słownik cytatów polskich i obcych (2005) that the proverb was used by Ireneusz Sekula commenting on the government of Hanna Suchocka in 1993.
The proverb has been very popular among learners of Polish since about 2013 but it has reached an even wider audience after appearing in the Netflix series Orange Is the New Black in season 5 in 2017.
Since then, various versions have been made up by Twitter, Instagram, TikTok and Reddit users.
The idiom is so popular that inspired dozens of products like pillows, T-shirts, mugs, prints and many more can be found on Google.