Setting up a stand in a busy place is one tactic that could work for many of these products, letting people test them for a moment and telling everyone who comes to the stand where the products can be bought. 

A less traditional route could be to set up a stand in the middle of nowhere and do the same thing with the passersby. In this scenario, you may want to video the promotion and post the video on Youtube and try to build a bit of buzz that way.

One thing one could do is use graffiti or bumper stickers to promote the product. One needs to be careful though, given some graffiti is denoted as criminal.

Another suggestion may be to use a video blog or video sharing site to promote the product.

One tactic often associated with guerilla marketing is a flash mob. You could stage a flash mob at a safe public location and haver everyone there consume one of your energy drinks. Maybe they could all wear t-shirts that advertise your product.