Four on the Shore

 By Edward Marshall

Sometimes these books are under James Marshall.  Because they are both the same person.

Lolly Sam and Spider make up stories on the lake to scare Willy.  They are terrible stories.  None of them are scary in the least.

 Each story is tacked onto the last to try and up the anti.  They're poorly written with simplistic explanations for things.  They're written exactly the way a story would be if it was told off the cuff by an 8 year old.

And it's hilarious, of course.  These books are just as good as anything else.  They're engaging for anyone over the age of four, but they're laugh out loud funny for anyone over 6.