Ah, singing. It's hard to sing well while actually riding so you might as well sing when you're stopped.

I call out whenever I see any other cyclist stopped. Most of the time they are all under control but sometimes they appreciate help. It's usually a case of needing my frame pump. It's surprising how may times I, or we on the tandem, have helped someone. I shouldn't talk - one time I swapped bikes just before commuting and forgot to transfer over my pump. Wouldn't you know, I had a flat that day. Another commuter going the opposite direct and with whom I've been exchanging waves for months came across the road and helped out.

Your brother puts his time to good use.