I didn't feel it myself, but my son-in-law and my own son said they were shocked when they touched the cemented ground in our backyard. We bought a new metal fire pit which we had set up and both men were picking up some wood off the cement when they were shocked. They said it felt like stinging and when they touched it repeatedly(don't ask me why)they could still feel it. It was just their hand and the cement. They were not touching water or anything else to create a flow.A few minutes later it was gone. It's been about a month and has not happened again.What could it have been? I'm a renter and I'm wondering if I should bother my landlord with this information when it's not happened again. This is a pretty old house.
Cement is not a good conductor so a live electrical charge from the cement is a near impossibility. But that doesn't rule out a static charge. If the humidity was right and enough friction from the wood to break some electrons free just might generate a static charge. But I have never heard of cement getting a static charge before but then again, I'm not moving wood a lot on a cement pad.
Could be several things. Problem is it is not consistent. If it were you could do things, like turning off the main breaker, to troubleshoot this. Since you are renting though your ONLY recourse is to contact your landlord and have him get someone to look at it. Thing is, the problem could very well be with the utility lines or even a neighbor's electrical service.
Maybe if they had rubber shoes and were carrying a live wire in one hand and touched the cement with the other, they could get shocked. If the cement is in the ground, it is pretty much grounded. No potential is coming from the cement, especially if they are standing on the cement and not touching anything else. Electricity does flow through cement though. In some jurisdictions, it's even okay to ground your electrical panel to the rebar in a cement foundation.
My guess is that they got splinters in their fingers, and it caused a shocking sensation when they touched the concrete.