People drive by my house without a muffler. My spouse says it's just "rednecks showing off." Is it true? What's up with that?

Some people are stuck in adolescence permanently. 

childish men wanting to prove something, its not that they don't have a muffler its the type of muffler.  In some areas they are banned call the cops get the plate number firs.t

Not showing off. Just idiots wanting everyone to know they're around. Most of us outgrow the attention seeking BS when we're at school! LMAO. I was once talking to a tradesman when a (loud) car went past, and I said how much his neighbours must love living next door to him with that racket. The tradesman got all embarrassed and said he knew the guy and that he was a very nice person. Somehow, I got the impression, the tradesman had a similar car and was embarrassed that his neighbours would hate him - that he'd never thought of it . . . 

That was fifty years ago.  Kids these days can barely afford a skate board let alone a car.  Maybe a few old peckerheads still do that.  You can easily recognize them.  They have one large hairy eyebrow, buck teeth and snot runs out their nose when they laugh. 

The mentality of this is typically a combination of things.

1. Insecurity- They fail to get attention on a personal level so they resort to boisterousness and obnoxiousness. Ultimately they don't have much to offer so they draw attention to themselves by any means. 2. They are supremely selfish and/or self-centered. Essentially trash people that don't give a toss that the sound emission of their vehicle is more than enough to cause permanent hearing damage, particularly to young children and infants.  3. Ego- Deep down they are weak and have some inferiority complexes, possible micro-penis, short physical stature or just plain undesirability. By being loud, obnoxious and flashy they are trying to exude strength and power where they have none. They try to fill the void in themselves with material things and simply want to people to notice these things. Ultimately, it's the epitome of man-child behaviour. On the plus side, this type of display comes with the convenience of a distinct audio queue that should alert others to stay well away from them.  

Not sure about rednecks, but people from rural areas that don't govern muffler requirements often go without or with a resonator or catback.

It's typically meant to intimidate, which means that the drivers likely lack self confidence and/or self esteem. 

can they afford a new muffler or exhaust system ! thinks your wife shouldnt judge people till she knows the circumstances .

Some people use their car for street racing.

it could be true

it could be true