Four bad unicorns by Rebecca Patterson

Roald Dahl Funny Prize winner Rebecca Patterson deftly handles the subject of childhood play and disability from her own personal experience of growing up with a disabled sister.
Frankie and her sister are UNICORN MAD! Today, they're playing their favourite unicorn game, but when their bossy friend Ada arrives with her brother to play, she takes over the game - and takes over the wheelchair - putting them all in unicorn prison! After all, they've been bad unicorns, haven't they?