Knock-Knock! Who's there? Hugo. Hugo who? Hugo wherever you want to go! And where will kids want to go? Where the knock-knocks are! Class clowns will find more than enough jokes to keep themselves and their friends entertained for hours on end. Here's just a small taste of the fun inside: Knock-knock! Who's there? Hatch. Hatch who? Gezundheit. One thing's for sure: children will be knock-knock-knocking at the bookshop door to get this!