버썩

Etymology 1
Perhaps related to Etymology 2 via an intermediary meaning of "like dry or brittle objects"?

Ideophone

 * 1) very dryly, aridly, parchedly
 * 2) while moving physically close to in an annoying way
 * 3) very suddenly moving to a large extent
 * 4) tensely, strainedly

Etymology 2
An intensive form of.

Ideophone

 * 1)  quite crunchingly; while stepping on, crushing, or snapping with a crunching sound
 * 2)  quite dryly, as to flake easily

Usage notes
is another intensive form of, and is considered more emphatic than.