Learn English – An alternative to “serious business”

One word is polymath.

noun
a person of wide knowledge or learning:
a Renaissance polymath

[ODO]

You could say he has an eclectic range of interests.

adjective
1 deriving ideas, style, or taste from a broad and diverse range of sources:
universities offering an eclectic mix of courses

[ODO]

The simple, all-purpose imprecation in U.S. English is "Drop dead!"—which is, of course, the usual stage before the soil-on-head stage. Christine Ammer, The American Heritage Dictionary of Idioms (1997) has this entry for the phrase:

drop dead An expression of anger, rejection, or indignation toward someone. For example, I should do all that work for you? Drop dead! This rude imperative is usually hyperbolic, that is, the speaker is not literally asking someone to die on the spot. {c. 1930}

Ammer then goes on to observe that drop-dead as an adjective, as in "drop-dead gorgeous," doesn't mean anything insulting: "Rather it means 'dazzling' or 'awe-inspiring'..."