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.
'Here mate you've got a hefty shite on yer shoe'
'Check that hefty fat burd'
'Here bud check oot ma new sannies, hefty cool int they'
'Your a hefty bawbag'
A Pollok term meaning large, a lot, very. Actually coming to think about it nobody has a f*cking clue what hefty actually means
Might come from the german "heftig", which means massive or intense.
Hefty fine = really really nice/good