* "He was _f_at and _f_lat of _f_lesh." (Describing Injun Joe)
* "There was a _s_oft _s_ound of _s_tepping on the _s_tairs." (When Tom is hiding in the haunted house)
These are just a couple of examples, and there are many more instances of alliteration throughout the book. Mark Twain used alliteration to add a touch of rhythm and emphasis to his writing, making it more engaging and memorable for the reader.