Napes of their necks.

[99bottles]

Ok, this is a little unusual. [Words deleted. 5jj]

The boys stroked the nape(s) of their neck(s) in embarrassment.

Is an 's' needed at the end of both those words (nape, neck)? It has occurred to me to write just 'napes' to avoid confusion, but the word 'nape' is used in the 'nape of the neck' form in all dictionaries I have consulted.

 

[cereal_chick]

You definitely can't say "neck" in the singular because that implies the boys share a collective neck which doesn't make sense. You might get away with saying "nape of their necks", but I would say "napes of their necks" because that feels most natural.

On which subject, why are you saying the word "nape" at all? It's quite an obscure word; it's not really in currency. Frankly it makes you sound weird. I would much rather say "the backs of their necks". Of course, this doesn't apply if you're not producing this, but then I have to ask why whoever did chose to say that.

[Not a teacher]

 

[Tarheel]

Pluralize both.