Not many people taking this seriously. Trouser and scissor are good candidates but still arguable. Nunchuck I like. You can have one chopstick – you can’t eat with it, unless it’s dumplings, but you can physically have one.

I’d suggest magnetic pole.

Other half

^
It’s making my head hurt thinking about that. I’ll stop.

Yes you can. Clap your fingers down against your palm.

I’m sure there’s a technical violation there somewhere.

Yin or Yang

Cone spanner.

I hadn’t realised we were supposed to.

Person arguing.

Not many people taking this seriously

O right I was not taking things literally enough (although I bet nobody who posted here has only one 5mm Allen key).

How about Molgrips, if you don’t have a pair then you just have a piece of metal which is not a Molgrip.

Or actions, you can never have one action.

Or faces, you can’t have just one of those

Took 4 posts to mention bikes on a biking forum, shame on you all.

Bikes
Biscuits
Boobs
Brain cells
Tea/Coffee

Guns (up to 8 now)
Bikes (6 plus the wife and child’s bikes)
Computers (4 actual x86/amd64 and a Pi)

Poos before leaving the house or before a big ride. 😆

quark

How about Molgrips, if you don’t have a pair then you just have a piece of metal which is not a Molgrip

Yeah, same as scissors.

Or faces, you can’t have just one of those

Doesn’t a solid sphere have just one?

Or faces, you can’t have just one of those

Speak for yourself, two faced…

Balls.

Hitler

Anything involving Marmite

the question was things you can’t have just one of not things you can’t have even one of.

people in a crowd

Mice
Geese
Am I doing it right?
Sides To a coin

math ?

A fork if you’re a Jekkyl though you can if you have a Bad Habit.

spoke

Bad Habit ….One fork

2018 Jekkyl apparently only with 2 forks

Universe

Doesn’t a solid sphere have just one? {face}

Mathematically a sphere has no faces, or an infinite number of faces.

spoke

Hundreds and thousands
Gloves
Twins, Triplets etc.
High class hookers
1 variety of Heinz Baked Beans

Twins, Triplets etc.

Nope.