Faux = false or fake. 'mo' is short for "homo(sexual)". Therefore "feaux 'mo' fashion show" means a man wearing clothes that might cause him to appear gay, even though he is not. Such as when a man accidentally (or purposely, for lack of clean clothes) wears an item of his wife's or girlfriend's clothing, not something as overtly feminine as a dress, but, say, some women's jeans, or a shirt that almost, but not quite, looks like a man's shirt.
THOMPSON: Look at the "feaux 'mo' fashion show". It looks like Jeff is accidentally wearing Sarah's CHIC jeans again!