Monumental

[Britney]

Of, pertaining to, or suitable for, a monument; as, a
monumental inscription.

[Britney]

Something thats really amazing. See [mental], sick, insane, [nuts], mad, [wicked], rude.
If something is mental but bigger/better

[Lanell]

Great in importance, extent, or size.

[Tanya Shivari]

To go monumental is to be infatuated by ones ego to the point of acting in a exaggeratedly pretentious way. People who go monumental say things or produce art that is boring and crappy, while at the same time being [ostentatious], [overblown] and pompous. This often creates a [mental breakdown] which causes the person who goes monumental to loose all contact with reality, and thus their very existence becomes utterly meaningless.