fifth wheel

US /ˌfɪfθ ˈwiːl/
UK /ˌfɪfθ ˈwiːl/
"fifth wheel" picture
1.

quinto incomodo, persona di troppo

a person who is in a situation where they are not needed or are superfluous

:
I felt like a fifth wheel on their romantic dinner.
Mi sentivo come un quinto incomodo alla loro cena romantica.
When they started talking about their inside jokes, I knew I was the fifth wheel.
Quando hanno iniziato a parlare delle loro battute interne, ho capito di essere il quinto incomodo.