Not a dumb question at all; it's actually asked enough that it made it into the FAQ (link
Can I give or receive feedback from a teammate or a friend?
Usually those deals are not eligible for feedback since they happen in person and you generally don't find out about friends or teammates gear for sale on PbNation.
Our feedback system is designed to instill trust within the community by demonstrating that strangers can work out deals from a distance. At the bare minimum you would need to say how you know the person and state that the deal went down in person.
If a teammate leaves you inappropriate feedback, make sure you get them to delete it right away. They have 48 hours to delete it. If they don't respond immediately and remove it, you need to report the feedback and ask for it to be removed. Make sure you say why you want it deleted. If the feedback is still there a week after you reported it, report it again and make a thread in the Talk to Mods forum. Remember, you both can be banned permanently for inappropriate feedback so act quickly. It only takes a couple seconds and shouldn't be put off because delaying could cause you to lose your account.
NOTE: PbNation feedback is only legitimate when the deal starts on PbNation. That means the deal has to be posted on PbN and it has to be seen there first to be within the rules. If they told you about it in person, over the phone or at the field then it is not eligible for PbN feedback.