Hefty is a term used in Glasgow, mainly the rough area of Pollok.
Hefty generally means, large, huge, big, very, alot.
It is generally used to describe a large object or something similar.

The word Heavy in these areas can also mean the same, as does Pure and are commonly found in the same sentance.

A Pollok term meaning large, a lot, very. Actually coming to think about it nobody has a f*cking clue what hefty actually means

Heavy, bulky

Might come from the german "heftig", which means massive or intense.

A very large penis.

meaning your a little bit large around the middle
ie Fat

sexxy, hot, cool, and can also be used when talking about a heavy situation