What's something that you've said that was meant innocently/jokingly but looking back was a horrible thing to say?

So I'm sitting in the last English class of the semester before finals. We have to meet two days for finals (it's a MTWHF class so while I'd have an 8 am final for MWF class, I'd also have a final for that same class on TH) and one of the girls in the back yells up to our professor "Hey! We should have a Christmas party for the day we don't have our final!" and our professor agrees (I currently go to a community college, by the way, so there are only about 20 people in this class... definitely not a giant lecture hall class).

We start planning what everyone is going to bring (if someone is going to bring something) and since it is a morning class there is a lot of breakfasty type pastries being suggested. But no one has said they're going to bring milk so I volunteer.

Then, a girl who sits in front of me turns and says, jokingly, "Milk is gross." My immediate knee-jerk reaction is to very loudly state, "SHUT YOUR WHORE MOUTH, MILK IS DELICIOUS!" She gave me a confused look and just turned back around. It wasn't until my friend turned to me and "loudly" said, "Ladypancake, did you just tell someone to shut their whore mouth, again?" (Basically saving my ass so everyone "understood" that this was something I "randomly" say all the time). That's when the guilt/horror came to the forefront of my mind and kept reminding me I had just told some innocent girl to shut her whore mouth, even though I meant it as a joke.

TL;DR: I told a girl to shut her whore mouth because milk is delicious