My mind reading is off a bit, but I think MikeMover may have been refering to the explosive oxidation of hydrogen, not thermonuclear fusion.

Its easy to generate enough hydrogen to make a loud pop with a dry cell and a couple of glass tubes inverted and submerged in water. Hook the wires to the dry cell and run one up each tube. Both wires will have little bubbles for around them. The wire with twice the bubbles will be the '-', I think. Sometimes a similar phenomenon happens when charging a dead batter.