So once I FaceTimed one of my friends, but this random dude answered
The only reason some random person would get your call is if you called the wrong number. 

Try verifying your friend's number. Make sure that's the only entry in her contact info. Also try getting the email she has for FaceTime. 

I've had it happen to me and the reason was I had a different number listed in my friend's contact info. 

Also, is there a chance your friend is just messing with you?