Not mother or baby related, but my and my boyfriend need some help..

My boyfriend has this "cousin" (they're not blood or marriage related) that we both do not like because of the fact that she talks crap on us and tries to take everything over from us but then tries to be our best friend. She also is OBSESSED with my boyfriend. Totally in love with him and so jealous of me, (it's weird, I know, her mom even told me that... We are both 17 amd she's almost 19 this month and acts 12) ANYWAYS, we do a Christmas gift exchange and everyone draws names and my boyfriend drew her name and he doesn't know what to get her. He doesn't want to get her anything that she can go brag about and never shut up about it. My mom said to get her socks, but I know she will walk around school telling everyone, "look what Shane got me for Christmas" and we seriously don't want to hear it. I told him to just get her some candy or something, but we both just dont know what to do. She also pulled me to the side earlier and said to not let him pick her gift cause she doesn't trust him and told me to pick it. No negative comments please. Y'all seriously don't know how she acts. You have to see it to believe it. All of our friends see it.