Conundrums

Tell me a word
that you've often heard,
yet it makes you squint
when you see it in print!

Tell me a thing
that you've often seen
yet if put in a book
it makes you turn green!

Tell me a thing
that you often do,
when described in a story
shocks you through and through!

Tell me what's wrong
with words or with you
that you don't mind the thing
yet the name is taboo.