These are all things I have heard in conversations over the last two days at work.
irregardless: Regardless of whether or not it's a stupid, made-up word, and irrespective of how clever you're trying to sound, you're still just a pretentious goatfucker.
a pigment of my imagination: How could you say this and not expect me to laugh at you? You stupid cunt.
"Pacific" when you mean "specific": Unless you're afflicted with an unfortunate speech impediment (in which case I apologise), don't ever say "Pacific" when you mean to say "specific", as happened to me today in t'office:
"I'm sorry Kav, could you be more Pacific?"
"Sure, no hassle" I replied, as I donned a pair of shorts and sunglasses and hopped on a surfboard. "Whoa, dude, check out these waves. Gnarly." I cried, balancing deftly on the edge of my desk.
Feel free to add your own hated words/phrases.