An overweight friend exploited by an insecure female to make herself look better in comparison. Said female will often hypocritically gush about the fat foil's "voluptuous" body, intelligence and sense of humor and claim she doesn't get why men don't appreciate her friend's stellar qualities. Needless to say, she will unceremoniously dump the foil if the foil loses weight and becomes even remotely attractive herself.
Megan: Wow, Charlotte looks so curvy in that dress. I don't why guys aren't all over her. You know, she'd be considered beautiful if she lived in Victorian times.
Guy at bar: Yeah, I get it, she's your "fat foil." Can I have your phone number?
Feeling ashamed after revealing a little too much of yourself to someone - allowing them to clear a view on your pettiness, your anger, your cowardice and childlike vulnerability - wishing that you didn’t have a deep disdain for who you think youactually are.
Jim- I’m feeling very Foilsick right now.
Bob-why?
Jim-I told this girl about how I’m feeling/my emotions.
1. (of a performance) very intensely fah-bulous, usually impromptu, solo piece
Even though it deviates from the planned performance, neither the fellow performers nor the audience/viewers object, because it enhances the original performance.
2. incredibly good, unbelievably good, defies expectations with how fabulous it is, utterly fah-bulous
Christine: That guitar sesh in the outro was foilissimo!
M: Oh you mean how he went off-script when he started jamming with his guitar but it only made the performance more incredible?
Christine: Yes! And also how utterly fah-bulous the actual jam was!
Dona: Foilissimo indeed!