Southern USA.
Ex. Two people need or want to purchase an item. Neither one has enough cash, credit to purchase the item.
If they go in 'havvers' they can purchase the needed/wanted item. Each person paying half of the total cost.
Fred sure does need that tractor for his farm work; he ain't got the money for it. Fred talks to Leroy about needing that tractor and his lack of money. Leroy is very happy! Fred, I need that same tractor and ain't got the money. How 'bout you and me go in 'havvers' and buy it?
The deal is made. Fred pays half; Leroy pays half the cost. The two men share the use of the needed tractor.
A person who has demonstrated they are part of a hive/collective "mind" or narrative, such as religious fanatics, highly partisan people, news site/talk show host fans, etc... Someone whose opinions can be known just by reading/listening to whatever they read or listen to regularly.
"She sounds like she's reciting republican party talking points, total hiver."
"He's a pure SJW hiver, if you've listened to him, you've listened to all of them."
"Like all hivers, his opinions on that come from others, he doesn't reason for himself."