A pedant writes.......

[Cadiz Seagull]

Shouldn't it be "plays-off" ?

 

[Aadam]

No, not really.

You wouldn't say books shelf would you.

 

[Waynflete]

I think in this case 'play-off' is a compound noun, so pluralised it becomes 'play-offs', unlike 'courts martial' where the noun is 'court' and the adjective is 'martial', so it is 'courts' that is pluralised.

I'm a massive fan of pedantry!

 

[Pevenseagull]

gins and tonic anyone?

 

[cliveh27]

I think in this case 'play-off' is a compound noun, so pluralised it becomes 'play-offs', unlike 'courts martial' where the noun is 'court' and the adjective is 'martial', so it is 'courts' that is pluralised.

Spot on.

 

[Nottseagull]

gins and tonic anyone?

I think this is more relevant. I think it depends on which word comes last, so "he tip-toes" and "he toe-punts" are both correct.