It depends. If I'm at a friend's house, I just take a little toilet tissue, wet it and clean my balls- excuse me, my Wife's balls as She owns them.
If necessary, I will cup a little water into my hand and put it into the tube so it runs out. Of course I then have to take more toilet tissue and clean myself and the floor. But normally I just worry about the balls when I'm out.
At work, it's a little more difficult because I have to leave the toilet stall to get to the sink and it is not a "one person at a time" bathroom. In that case, I will still clean my balls with toilet tissue but not wet the tissue first. Sometimes I will though. IWhen you flush the toilet, the water that runs out from the rim at work is really clean water as it has not touched the toilet bowl yet. I know it sounds disgusting but it's actually clean as long as it hasn't yet made contact with the bowl.
If I have to I will take off all of my lower clothing while in the stall and then I will again take some bunched up toilet tissue and soak it. Then I'll sit and squeeze the tissue so the water runs through the tube, rinsing it out. Then I'll dry and get dressed. It's a minor annoyance but it works. Note: If while wetting the tissue, it touches the toilet, just toss it in the bowl and grab more paper. Make sure your clothing is off and set out of the way so they don't get wet.