Riddonkulous

Babies have this reflex, so a pacifier is given. Maybe you'll be called me, if a bad riddle you have written. Replace my first with another, some good fortune you will find Swap my first again with another, and quack, quack, in a line. Once again replace the first, with a certain letter and i'll be A word that is a no-no and offensive to most people, but i think it's pretty versatile so I don't really mind it, lol. Ugh, alright... see?