Well, here's a brief story where I did speak up. I'm not very proud of the language I used, but we had a similar experience with a rude person at L!M!A! as well.
It began to rain in the middle of the show, and the show was ended early. My niece is in a wheelchair and because as anyone with sense knows, when thousands of people are exiting a theater (under duress, because people were getting wet) you can't just push a wheelchair into the middle of it. You have to wait for people to clear out.
We were patiently sitting in our assigned seats, and this obnoxious woman and her daughter tried to save themselves a whole two feet of walking (literally, two steps) by cutting in front of my niece and I who were sitting. Now, this wouldn't have been much of a problem had my niece not been in a chair, but the foot rests go right against the seat in front of you. In order to get past us, the woman had to literally CRAWL over my niece. All to save two feet of walking!
As she was doing it, I said, "Excuse me?" twice. She just stared ahead and pretended to ignore me.
She stumbled over my niece (again, we were IN OUR SEATS), sticking her large butt right in her face, and led her snitty little daughter with her. In reality, it took longer for her to "jump" over my niece than if she'd just gone the normal way.
Anyway, I still hadn't lost my temper, but did say, "Next time, please don't step on a child in a wheelchair."
She looked at me, gave me one of those fake patronizing looks like I was being unreasonable in asking her not to jump over a kid in a wheelchair, and then rolled her eyes as she started to walk away.
So I said, loud enough for those around me to hear, "Inconsiderate witch..." while looking straight at her. (And no, I didn't say "witch" LOL). She stopped dead in her tracks, turned around...and realized that it wasn't worth trying to fight with me because she was completely in the wrong and slinked away.
I do regret using the language I did, but that woman was just so dang arrogant she thought that climbing over a child in the wheelchair section (that didn't even save her any time in the long run) that I just couldn't help it. I'm sure her kid was embarassed, but I'm sorry - in the long run, that's a good thing. The kid will learn not to be like her "we're better than everyone else" parent.
While it's never "okay" to be rude back to someone, sometimes it just feels...appropriate. And, thankfully, "witches" like that are very few and far between, and the vast majority of people understand how to be decent human beings.
NED
. I felt so bad for that poor kid and his parents that I had to fight hard to keep from crying. People in line were yelling at the woman and a CM stepped in to speak to her. I really wanted to smack that nasty old bat 
for 10 minutes and then tell me if they want to have me stand behind them in line for the next 30-??? minutes it takes for the ride 
. I don't use the GAC to get on the ride first, just so that my child can wait for the ride in a quiet area without all of the sensory input.
