The other side of the coin noun phrase
Used to refer to the opposite aspect of a subject or a situation
I like wearing white clothes, but the other side of the coin is that they easily get dirty.
Sometimes, I get lonely when living alone but the other side of the coin is that I have amazing freedom.
Working as a freelancer gives you flexibility in work time, but the other side of the coin is that you don't have a stable salary.
Holding opposing opinions on an issue or in a situation
1. Soneone tends to speak in unkind and cruel way that is likely to upset or hurt someone else.
2. The fossil tooth of a shark
1. Many people doesn't want to make friends with Sue because she has a serpent's tongue.
2. A: 'My thesis will center on a serpent's tongue.' B: 'A serpent's tongue? What does it mean?' A: 'A serpent's tongue means the fossil tooth of a shark.'