If you're just talking about static electricity, like from wearing socks on the carpet or things like that, here's a general guideline: If you can feel it, it's 3000 volts; if you can hear it, it's 5000 volts; and if you can see it, it's 8000 volts. That's just when talking about static discharge through air, like touching the door knob after walking across carpet in socks. Very low current available, but you can get really high voltages just from static build-up.
For other things like from batteries and real energy sources, it depends on both the current and voltage (like pseudo said), which can both depend on a LOT of things. It's also different for every person as far as sensitivity, as well. Everyone reacts differently to electricity.