I can't tell how irritating it is when I speak Spanish to people in my new neighborhood (where Spanish is basically all you hear). In my head, I look/sound like Peggy Hill (from King of the Hill), which makes me cringe, even though I actually can speak Spanish. And I don't want it to seem like I assume people can't speak English.
It annoys me when people say they're "free all week", so you suggest 3 potential days and ranges of times to meet, and then they counteroffer with a totally random other time. It pings my sociopathy meter.
Scheduled my Time Warner service disconnection (which you can only do over the phone, which is total bullshit). At the end of the call, the woman encouraged me to "keep Time Warner in mind for my future home telecommunications and entertainment needs".