cat bat and tan can ban pan ran ram man mat rat yak dog log nap cap tap pop top sap gap map fan you Jew say may who hit mit car bar tar jar bus gas the tad bad fad sad fat pat pad hat lap new dew sue sew ask jot pot lot cot dot not are had sat
tattooballooncommitteekeennessraccooncoffeebookkeeper
vacuum and continuum
Mississippi
balloon coffee
Well, there's probably more than three. Right now I could only think of "balloon" and raccoon though, assuming that you meant those double letters have to be next to each other.
The next three letters in the sequence WATNTLIT are "I", "S", and "A". This sequence represents the first letter of each word in the phrase "What Are The Next Three Letters In This?" The pattern continues by following the same structure.
The next three letters in the series "gtntl" are "e", "r", and "s". This sequence corresponds to the first letters of the words "get", "to", "next", "level", which suggests a pattern of moving through each word. The completion of the series leads to "get to the next level".
Multiplication
tattooballooncommitteekeennessraccooncoffeebookkeeper
vacuum and continuum
Mississippi
bellhop
"a" & "b".
bellhop
quizmaster
quizmaster
balloon coffee