Formal:
* It was disrespectful of him to interrupt the speaker during the presentation.
* Her behavior towards her elders was considered disrespectful and unacceptable.
Informal:
* That was a disrespectful thing to say about her, even if you didn't mean it.
* I found it disrespectful that he didn't even acknowledge my presence.
Specific examples:
* The student's disrespectful attitude towards the teacher resulted in a detention.
* It's disrespectful to talk over someone when they're trying to speak.
* The way he treated her was disrespectful and inappropriate.
You can use "disrespectful" to describe an action, a behavior, or even an attitude.