I think it was plausible
I came in after they had already done that one, but I got the impression it did something. The good one was the methane soap bubbles.
Pumped methane at low pressure through a lawn sprinkler into the bottom of a 5-gallon bucket full of liquid soap. Since methane is lighter than air, the column of bubbles kept growing up to about 15 feet high. Then they hit it with a match. FWOOM!
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Purveyor of Doc Hope's [link|http://DocHope.com|fresh-baked dog biscuits and pet treats].
[link|http://DocHope.com|http://DocHope.com]