Nonchalant means rude and not proper so if someone would have that attitude it would mean that person wasn't a very polite person.
Not necessarily but a nonchalant attitude can be viewed as noncaring or detached.
Mood, Moody. melancholic, mean, miserable,
You pay attention and become interested.
If you appear before the judge with a smug, nonchalant attitude, he's more likely to impose the maximum sentence.
Nonchalant means not concerned or indifferent.
To be nonchalant about something means that someone is very easy going about something and acting as if it is easy or is not really that big of a deal to them.
Connor MIlls
The man was nonchalant
Nonchalant was born on 1970-10-18.
Nonchalant, he lifted her skirt, (which was hanging on the clothesline).
Example sentence - He acted quite nonchalant about the evening with her.
From the Related Link: 1. Uninterested because of frequent exposure or indulgence.2. Unconcerned; nonchalant: had a blasé attitude about housecleaning.3. Very sophisticated.