Here are a few things that come out of the mouths of well-meaning people, but which drive me nuts:
Time Clock: I work on salary, but many of my co-workers get paid hourly, and must punch in and out. The device they use to clock in is usually referred to as a "time clock". Why is this? Every clock is a time clock!
Literally: I once heard a news reporter say "people here in this small town are literally bursting with pride that this young man from their hometown has won a Gold Medal..." Wait! Did you say that people are literally bursting? Like a whole town is full of exploding people? Shouldn't this be front page news?
Awesome: I also once heard a waitress say that the tortilla soup is "awesome." No, it's not. It might be really good. But save the word "awesome" for God, or a volcano, or the Grand Canyon, or a cure for cancer. Your soup is not awesome. It can't be.
ATM Machine (because the M stands for Machine)
PIN Number (because the N stands for Number)
Hot Water Heater (it's a water heater, not a hot water heater. Why would you want to heat hot water?)