Words and phrases that I just can’t use, either at all or at the very least without rolling my eyes, giggling, or being loaded with sarcasm:
TIA (for “thanks in advance”)
return on investment (or even worse, just saying “R.O.I.”)
just a heads up
poo-poo (as in, “he poo-poo’ed that idea”)
outside the box
massaging the data
buttock (weirdly, this is only true of the singular. I can say “buttocks” just fine).
What words bug you?