foilissimo

Adj.

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!