I have found no better lubricant for masturbation than my own pre-cum. Problem is, I have plenty of it sometimes, and not nearly enough at other times (usually when I have to do it in a hurry). I would like to store some up to use for those dry times by "milking" the stuff into a small glass vial or something. However, I wonder about whether it would "spoil" or start growing bacteria, etc. If so, would that matter, since I would be using it externally on my own penis? Any ideas on how best to store it?