Euphemisms are things that one should not really waste time with.
But if you are hell bent on using it, you might as well get it right.
Take this for instance: Horizontally Challenged
What is with the usage of the phrase? When a vertically challenged person lacks height, a mentally challenged person lacks mental skills, a horizontally challenged person.. well should lack width.
So whats with calling FAT people horizontally challenged?
Fat people should be --> Horizontally Challenging.
Look at the image below,
Who do you think is the frikking challenger here?