Dps favourite book was one dd2 had for about 3 weeks and drove us all completely insane. It was called 'Up and down' and involves escalators in a shop.
The text went..
mum went up
dad went down
dad went up
mum went down
oh no said mum
dad went down
mum went up
'up and down!' said dad.
Dp was delighted by dad declaring 'up and down!' for some reason, and annoys us all by saying it for no apparent reason.