or is that Cole Porter?

No, no DubDub, a colporteur is a guy who runs around selling bibles. Now if you're talking about some cold Porto, I'll be right over with my glass.

You can go to a bicycle shop and obtain - for about twenty bucks - a tire inflater that uses carbon dioxide cartridges. So, you can do the waterfall experiment AND have a way to pump up your bike tires quickly, AND stop an assailant in his tracks by yelling, "Freeze, sucker," then uh, well, freezing him.