<DIV><p>Knock, knock.<br>Who's there?<BR>Gorilla.<BR>Gorilla who?<BR>Gorilla cheese sandwich for me, will you, please?<BR><BR>Knock, knock.<BR>Who's there?<BR>Water.<BR>Water who?<BR>Water you waiting for? Let me in.</p><p>More than 400 classic knock-knock jokes from the pages of Highlights magazine and other sources will set off laugh attacks every time kids open the book.<BR></p></div>