Okay kiddo, so a situational offender is someone who only does bad things in certain situations. It's like how you might only act out in class when the teacher isn't paying attention, but you're usually a really good student.
Some grown-ups might also only do something bad in certain situations. For example, they might steal something if they're really desperate for money, but they wouldn't normally do that.
It's still not okay to be a situational offender though, because doing something bad is still wrong no matter what the situation is. It's important to always try and make good choices, even when it's hard.