On a recent flight IAH-PIT on a jungle jet, I was seated in the exit row with a large gentle. In this case - he was not obese - so size did not matter. He squeezed into his seat and with the armrest down - I was comfortable.
The flight was full - I repeat the flight was full.
30 minutes into the flight - and I began to notice the most fouling selling flatulence. It would not go away. It was worse than spoiled cabbage that had been left to rot with a spirit of skunk and carrion thrown in. It was disgusting

I was nauseated.
I turned up the air to blow directly in my face - then I fanned myself. Embarrassingly a person in front of me looked back at me fanning and I think she though the aroma was mine. I said, "I did not do it."
Finally, there was a noise associated with the obnoxious gas. I looked at the man beside me and in an effiminant voice he squealed "Sorry." I thought to myself - "Sorry hell".
He did it once more (made a sound like a clap of roaring thunder) and I looked at him and said loudly - "DAMN. Can you cut it out?" People started laughing. He apologized and said he ate something that must not have agreed with him. I said, "Apparently not."
He finally got up and went to the bathroom. When the door closed, people started laughing and talking and saying - Nice job.
I was embarrassed - but it was FOUL.
I came home - took a shower and washed my clothes.
How would anyone else have handled this situation?