Back when I was in grad school, as a TA I read a student's paper that referred to "vast suppositories of power." (I think he meant "repositories.") I just circled the word and wrote him a note suggesting he look it up before using it again.
Pretty sure I would have burst some blood vessels laughing if I'd seen that.
A few of my pet peeves:
Two jobs ago, I worked for a great company and really enjoyed my time there - except for the widespread use of the word "timely." No clue why nearly everyone did it, but they all said things like "Be sure you get that report to me timely" and "We need to perform this task timely."
Utilize. Substituting that word for "use" does not make anyone sound smarter.
One former boss used to say "flustrated" instead of "frustrated" and another repeatedly talked about handling touchy situations with "kit" gloves.
Not a pet peeve, but amusing: The head of HR at a former job came from the East Coast (US) somewhere and didn't know a word of Spanish. I'm in southern Arizona and my place of work at the time hired a lot
of Spanish speakers to handle international calls. We were planning a big party for the employees at one point and decided to have a Mexican fiesta theme. At a center meeting, the head of HR asked brightly, "So how is planning going for the big Mexican fiasco?"