i hate my sisters boy toy

so my younger sis got this guy she really likes and he's always around the house, which is annoying af. i mean, its not like he has any job or anything, just hanging out with her all day long, and i dont even know what he does for money but im sure its shady because hes always sneaking around and talking to my sister in private rooms. one time i saw him on the roof with a weird antenna setup that looks suspiciously like something from a spy movie lol. plus hes older than everyone by at least 10 years which is just weird, and it feels like im stuck babysitting some stranger when i should be hanging out with my friends or chilling in my room. today we all went to the beach but he decided to bring his own private lounge setup complete with a canopy and lots of snacks which made me feel left out because i couldnt even share space on the blanket without feeling like an intruder, even though hes not actually mine lol. now everyone thinks hes cool and fun but honestly im just tired of having this guy around all the time and wishing he would leave already.