For the last 2 years or more, I have ended the bedtime stories with the twins by reciting Mother Goose's "Wee Willie Winkie". For those of you who don't remember, this is how it goes:
Wee Willie Winkie runs through the town
Upstairs, downstairs in his nightgown
Rapping on the windows
Crying through the locks
"Are all the children in their beds
It's past eight o'clock!"
I knock on the wall without the twins seeing me, gasp, and cry out "It's Wee Willie Winkie! Run!". My little angels leap into bed and demand hugs and kisses.
The other night the twins and I read books on Katie's bed. When we were finished, I recited the poem, gasped, and warned them of Wee Willie Winkie's imminent arrival. Bethie raced to her bed. Katie yelled "Don't worry, Bethie, it was just me". She then knocked on the wall to demonstrate. Bethie, feeling very much relieved, climbed back into bed with Katie.