a) Some of the most popular activities with my friends are hanging out, eating somewhere or watching a film together.
b) The latest "crazies" for me and my friends are discovering underground tunnels and exploring ancient buildings during the night.
c) I think that all activities that I do not like are a waste of time, because instead of doing those, I could spend my time doing something that I really enjoy and I would learn more about my passions.
I hope I was able to help!:)