Captain Underpants is not a book or a series of books: It is in fact an obsession! The books in general have three principal characters- George, Harold (two mischievous boys with new tricks up their sleeves daily!) and their headmaster Mr. Krupp who is mean yet the victim of the boys' pranks!
The books are targeted for young readers ( 6yrs+ ) , BUT a word of caution : They shouldn land in the hands of these kids! :P The humor and language of the text is definitely not suitable for such young readers as it can be impressionable on young minds. However, adults or teens will thoroughly enjoy the jokes and wise cracks. The books in general do not have a very intelligent plot, they are simple almost bordering on stupid at times but then that makes them one of a kind. The titles of these books are also interesting: they are too lengthy to be true( you could decipher half the plot)!
Verdict: Do buy at least one to have a day of laughs (laffs) ! I couldn stop laughing while reading this book, it was total nonsensical and I loved the idea behind these books.