三人行必有电灯泡
[sān rén xíng bì yŏu diàn dēng pào]
The name 'San ren xing bi you dian deng pao' translates to 'in any trio, there is a light bulb'. It comes from the common expression for the 'third wheel', referring to a third person in a couple's situation or when someone feels out of place in social contexts usually because they are alone while others are paired up.