I have diapers on / I'm wearing diapers

[curiousmarcus]

Go pee in the bathroom before we go out.

I have diapers on! / I'm wearing diapers!

Should it be I have a diaper on / I'm wearing a diaper?

 

[Rover_KE]

Use the singular, unless he's wearing two nappies (BE word for diapers).

 

[Tdol]

I'm wearing nappies does sound OK to me as well as the singular.

 

[konungursvia]

To me the plural sounds fine as well, by analogy with shorts, underpants, trousers, etc.

 

[Charlie Bernstein]

In the US, diapers can be singular or plural. We also use the singular, diaper.

But most kids in diapers don't speak in complete sentences yet.

 

[emsr2d2]

The plural would work for me if this exceptionally linguistically-talented toddler were likely to say "No, I don't need to pee in the bathroom. I'm only 2. I'm still in nappies!" Here, "in nappies" is a general term for "not yet potty-trained/toilet-trained".

A: Is little Billy potty-trained yet?
B: No. He's still in nappies day and night. (Sigh.)

However, if the child is (as is normal) is wearing just one, then "I'm wearing a nappy" is the only natural choice for me.

 

[Skrej]

"I'm wearing a nappy" is the only natural choice for me.

I would argue that diapers (and by extension all clothes) are an artificial choice; the only truly natural choice would be nakedness. Unless maybe you used palm fronds for diapers....

The appropriateness of such a natural choice is of course a separate debate.