Wasn't familiar with this concept. Funny though: in my language, "5th wheel (on a car)" refers to someone being as useful as... well, the 5th wheel on a car, i

Wasn't familiar with this concept. Funny though: in my language, "5th wheel (on a car)" refers to someone being as useful as... well, the 5th wheel on a car, i.e., not useful at all. The "on a car" part is often left out. (Sidenote for anyone wanting to argue the usefulness of 5th wheels: I'm not my language designated responsible for sayings and common phrasings. Also: 5th wheels tend to be the emergency spare wheels - which obviously do have a use.)