For readers who want them, there are fart, butt, and bodily function jokes galore. There is even a prolonged broccoli flinging episode in the restaurant. Younger readers will find it especially interesting that the aliens farts can simulate a lot of different Earth smells, from McDonalds to cinnamon buns to less pleasant aromas.
If science fiction has taught me nothing else, it's that you NEVER give aliens the smaller corner to claim as their own, because they will just start to take over! We need to look no further than Faulkner's The Assault or Walden's Earthfall for proof of this! While this book has more in common with humorous speculative fiction like Emerson's Society for Alien Detection or Kloepfer's Into the Dorkness, the message is clear: be careful of aliens, especially if they eat your couch cushions and then barf them up repeatedly!