Regarding one's own behavior or oneself as "awesome" when in fact the behavior is misguided, or embarrassing, or one is really living a thinly-veiled life of mediocrity and fear.
The hipster was convinced that he was completely awesome, but those around him knew he was fauxsome, with no real ideas or action to back him up.
When something is deemed terribly and irrefutably wrong or unbecoming.
Rog bragged to everyone about how he was going to jump out of the plane, but he pissed his pants and chickened out at the last minute. He was so fauxsome.