I saw a bloke hunched down beside his bike along a lane last summer and I shouted out to see if he needed help. I didn't catch his answer but he sounded in distress so I stopped a few yards down the road and asked again if he was alright. 'Eff off, I'm taking a dump,' came the reply.
I made myself useful before Christmas tho when I saw a woman wheeling her step-through bike with a basket on my commute. Turned out the LBS who'd fixed a puncture for her hadn't tightened the nuts on her rear wheel enough and it'd come loose a couple of miles down the road. Luckily, I carry a 15mm spanner and was able to help. Feels good when you can help someone out.