Rare slang used in Billings, Montana to describe something wild, busy, packed, or jammed.
The origin of the word is from the two busiest roads in the city, Central and Main; compared to the other roads that are usually pretty empty, it created a stark contrast
to the point people started referring to thinks as "like central or main" which
over time, fused into "like centralmain", then just "centralmain"
Like i said, very rare but its still a used word in downtown Billings, Montana