all right, we have all seen the lovely family tree, but what does it all mean? i have been analyzing the trees at the back of rotk for hours. i have never been very good at figuring relations much past first cousins, but here we go.
p.s. if i'm wrong, tell me.

basics:
pippin is peregrin I of the infamous took family of the shire. he is the son of thain paladin took II and eglantine banks. he is the youngest and only male of four children. pearl (15 years older), pimpernel (11 years older), pervinca (five years older) are his siblings.

married life:
pippin eventually does marry. his wife is a hobbit by the name of diamond, of long cleeve. she is five years younger than peregrin. together they have one son, faramir I, named after the steward of gondor, whose life pippin helped save.

the other famous hobbits:
really. down to business. how is pippin related to the other hobbits?
this is where things get a bit hairy (footed) at times. let us begin with pippin's best friend merry. merry, born meriadoc brandybuck, was the son of saradoc brandybuck and esmeralda took. esmeralda was the younger sister of pippin's father, paladin II, making merry and pippin, first cousins.
brandybuck connection, check. next, the bagginses.
figuring pippin's relation to the famous bagginses, is a bit more difficult. first- bilbo. bilbo was the cousin of adalgrim, pippin's grandfather. this would make paladin, pippin's father, bilbo's first cousin, once removed.
therefore- pippin is bilbo's first cousin, twice removed.
all right then, how about frodo now? this was the most complicated one. going off of the took family tree, and the minor quote from the movie- i think we have it figured out though.
ok. adalgrim took, pippin's grandfather and frodo's mother, primula brandybuck, were infact first cousins (primula's mother, mirabella, was the younger sister of hildigrim, adalgrim's father), making paladin II, pippin's father, and frodo, second cousins. paladin's children, then, are second cousins once removed to frodo. pippin is frodo's second cousin, once removed.
this is how pippin is related to frodo on frodo's mother's side, but, infact he is actually related to him through drogo baggins (frodo's father) as well (inbred little buggers, aren't they). aldagrim took (again, pippin's grandfather) and drogo baggins were second cousins (rosa baggins, hildigrim took's [pippin's great grandfather's] wife, was the cousin of drogo's father, fosco baggins, see rotk appendix, baggins family tree) this would make, paladin (pippin's father) and frodo third cousins. paladin's children, therefore, pippin, become, frodo's third cousins, once removed.
now in the movie quote pippin claims to be frodo's third cousin twice removed, but i really can't figure the other removal. as far as i can see there is only one generation between frodo and pippin, not two. if any one else is bored and wants to analyze this point, and if you come up with another answer, please tell me.
now i saved samwise's relation to pippin for last, for it is easiest. they're not related! muahhahaha. the three families, baggins, took and brandybuck, were esteemed families of the shire. the gamgee line, however, until the after the war of the ring, had not until that point, been held in any great honour. i am assuming also, until that point, the "higher" classes, didn't mix with the "lower" in such permanent matters as marriage. stinking class oriented hobbits!
in the end though, pippin and sam do end up in-laws of sorts. peregrin's son, faramir I, marries samwise's sixth child and third eldest daughter, goldilocks. so whatever the father of the bride and the father of the groom are to each other, that's the relationship sam and pippin share.

... x