Other book series for a kid who likes Captain Underpants?

My son who will be starting 2nd grade in the fall was not a big reader until he discovered the Captain Underpants series about a year ago. He read the books voraciously and loves to talk about the characters and the plots. I think he is attracted by all the weirdness, the inventions, the dinosaurs and bionic hamsters and space aliens.

(I find the books very enjoyable myself, for what they are. I can’t be the only adult fan here, can I?)

He has read all the books in this series multiple times already. More are on the way but in the meantime I would like to try to get him to expand his horizons some. A series we discovered recently that has definite potential is The Time Warp Trio books. I like it because it is actually somewhat educational and is written at a higher reading level than Captain Underpants, in the sense that it is challenging for him. He appreciates the humor and again the time travel and other fantastical elements.

Does anyone know of other series similar in style and themes to Captain Underpants, at the same or harder reading level? Thanks in advance.

In a year or two you could try the Mad Scientists’ Club collections of short stories… concerning a rural [Montana?] club of clever high-school-age boy “scientists”. They’re wonderfully written, with engaging characters, goofy inventions, pranks, and adventures.

I doubt your boy would be up to the challenge of their level just now, though.

How about the A Series of Unfortunate Events books? They’re very quirky and have inventions and humor and acts of derring do.

I hate to say it (not really), but there are no books out there that a second grade boy will prefer over the Captain Underpants books. Dav Pilkey is a genius for combining challenging children’s literature with, well, butts and poopie jokes. Some of the vocabulary in his books is a reach for second graders kids, and the silly stories really motivate them to lear the words.

I helped my son’s second grade teacher during reading time last year, and while the boys ate up the Captain Underpants books (sorry for the disturbing visual of that metaphor), the Bailey School Kids series was a close second in popularity.

I’d recommend Daniel Pinkwater’s “Snarkout Boys” books, although he might be too young for those. You can also try “The Hoboken Chicken Emergency.”

The Wayside School books by Louis Sacher are funny. Also the Black Lagoon series by Mike Thaler and Jared Lee. Both have the same combination of funny text and pictures.

These don’t have the graphic element of Captain Underpants, but my son (who loved the Pilkey books) also likes all the Bruce Coville “Alien” books. They have titles like “I was a Sixth Grade Alien”, “Aliens Ate My Homework”, “My Teacher Is An Alien”. Some are parts of series (sixth-grade alien has several sequels, ditto the homework one) and others appear to be standalone.

And of course Pilkey also wrote several books about Ricky Ricotta, which, I think, include a mouse with a robot. Those aren’t quite as gross-out funny as the Captain Underpants but they do have the graphics.

eta: Oooh, oooh - I just remembered “The Day My Butt Went Psycho” (which also has some sequels). It’s a must-read for any Captain Underpants fan.

My “Captain Underpants” loving six year old also adores the “Bailey School Kids”, FWIW.

Thanks everyone for all the suggestions, I will have to look into them. The only ones I have read are the Mad Scientist ones, which I agree are probably a few years above him. Some of the others might be as well.
(Oh, I forgot to mention my son also discovered some “Calvin and Hobbes” collections we had lying around, and he loves that too. Anything where little boys are getting away with something.)