The book I recommend  is “Marvin Red Post: Is He a Girl?” by Louis Sachar.

There is a boy named Marvin and he is at school. This girl says if you kiss your elbow you will turn into a girl. Then he went home it was night time and he was trying to kiss his elbow and it worked. But now he is  acting like a girl. If he kisses his elbow again, would he turn back into a boy? well read this book to find out more . And I love this book because you never now whats going to happen  and there are some surprises you might see.