so when are you bringing your unicorn to the library?

Like other libraries, we have a very exciting St. Patrick's display (it has a rainbow).  For part of the display, I taped a black hole pastoral landscape cat cauldron to the wall, and set out a bucket filled with paper shamrocks that actually look like shamrocks.  There is a sign prompting kids and parents to write on a shamrock what they are lucky to have.  I am greatly enjoying this interactive display and have heard some interesting responses (and not just about what the black thing is on the wall).

Today's interaction, however, takes the cake.  

Mom with son (5 or 6 years old) and daughter (toddler) approach desk and look at the shamrocks curiously.

I explain their purpose.

Mom asks daughter what she is lucky to have.  Daughter says brother's name.

Mom asks son what he is lucky to have.  He says, 'unicorns.'

Mom tells son he has to spell it on his own.

Son shouts, "ok then, a dog!"

Mom sighs and says, "but we don't have a dog."