Witnessed: catcalling

I was walking with my colleagues back to the office after lunch and both of my team-mates are girls. A bunch of boys were on a motorcycle and rode past us and cat-called them. My colleagues were visibly upset. I tried to stop them [the boys on the bike] and called after them. My colleagues told me this is ‘normal’ behaviour and I should just let it pass. Can’t believe that in this day in age boys get away with treating girls like objects! This needs to end! For my friends, my nieces, for all!