Is it normal to bring your college buddy on vacation with you?

My parents, me, my aunt and cousin, are planning on taking a trip to Europe after I graduate from college (which will be in 1 year). There's a chance my cousin, who's a girl, will bring her friend on the trip. Her friend is a girl. Now my question is this: would it be normal or gay if I were to ask one of my friend's (who's a guy) to go on vacation with us? I'd just like to have someone to talk to on the trip besides adults. My cousin and her friend are 5 years younger than me, so it would be kinda weird for a 21 year old guy wanting to hang out with 16 year old girls the whole time. If my cousin doesn't bring her friend, then I wouldn't ask my friend to come. Do guys in their early twenties even go on big vacations together with their parents? I know two guys who did, but they were 16 and in high school at the time when they went to the Bahamas.