Can getting someone's IP address be illegal?

[Emma]

Call me all the names you want, lol but I'm so called "new" to getting IP addresses over xbox live. I'm a girl ( and please don't take it the wrong way I'm not trying to be sexy or anything I just want to have fun with my friends.) and I'm used to getting hit on by littlekids, and shamefully adults as well. To sum it up, I have a program that gets their ip and their location bla bla bla. And sometimes if I'm lucky a Facebook page pops up or something so I get their name too, but that doesn't matter. I would just say their name so they freak out, and then they leave. I'm not threatening them, or anything close to it. I don't say their address in a public lobby, only in a party. I just like their reactions and I don't really mean to harm anyone. I'm taking threats from people like " that's illegal I'm calling the police" lmao but I just want to make sure, is it illegal to take ip's? There's websites for it, so why not? If it's not illegal, what can I say to ensure them of it?