I actually don't really have any issue with fat people. They can do whatever the hell they want with their bodies.
And I honestly don't have any issue with stupid people - they can do whatever they want to themselves and go on however they like - American is a free country.
What annoys me is when that behavior then has a direct effect on those around them. It is one thing to do whatever the fuck you want for yourself, but when you start expecting everyone around you to drop everything and respond to you, that is where I find issues in it.
I was getting on one flight and the fact that the line wasn't moving fast enough bothered a fat old lady behind me. She said "I don't know what they are waiting on, they are just looking around at the birds."
Her voice was grating and whiney - it took much restraint for me not to turn around and say "wow! your holiday spirit is contagious!" and then shake her to death just to reduce the weight of the plane.
The real beauty was that she was sitting right next to me on the flight as well. She was making little whining and complaining noises the whole time. Fortunately it wasn't a long flight.
There were a ton of instances of it. People standing in the security line that were knocking me around simply because their fat bodies didn't do well in crowds.
And those people were audible voicing their concern that they would miss their flight due to the security line - also noting that they didn't see why they had to get their so early for their flight.
Then they would ask each person that they saw if they could be moved to the front of the line since they had been waiting for "hours" (even though they got in line at the same time as me and I had been there less than 45 mins).
Then they refused to take off their shoes because "I have a hard time reaching my shoes."
It was all very trying.