pull out the uke

Used when somebody needs to apologize for something they did, especially when they don't believe that they need to apologize.

Ex 1: "Apparently HR says I need to pull out the uke for making a bunch of weirdly sexual comments"
Ex 2: Man 1 - "Did you hear that Jason called his wife fat?"
Man 2 - "Yeah, he had to pull out the uke."