If I talk to someone on a music forum, then you could talk about that music artist. Then from there if they list on their profile that they like the soccer team, Barcelona, and the movie, The Matrix, (for examples), then I send them a message:

"Hi, so what's your favorite album by [music artist]? Mine is probably _____. Have you been catching up on how Barcelona is doing? I also like the Matrix movie. If you were in Neo's position, would you choose the red or blue pill? I would probably pick blah blah because blah blah.

-Matt"