Our college was a bit "different" in that it was divided into specialist "shops". This consisted of separate workshops for each major area of the car - so there was a transmission shop, a body/chassis shop, an electrics shop, a power unit shop (you get the idea I'm sure. Anyway, the engine shop consisted of a small Froude dynamometer (water brake) to which was coupled a six cylinder Vauxhall engine used for various running demonstrations and exploring the relevance of timing and fueling. Then there were various engines on stands, all were runners, which were used to do fault finding and basic service procedures. One of these was a flat 4 VW which it was very easy to remove an HT lead on. The, rather silly, trick was that when a new student came into the shop you would take the HT lead off and hold it in your hand behind your back - engine running of course, not a pleasant experience for the "trickster" but bearable because you were prepared for it - then, as the "new boy" approached, you would say something like "look at your nose" or "what's wrong with your nose?, come here." Then, as he approached you'd extend your index finger and point at his nose until the gap was small enough for the spark to jump to his nose! The result was never really very funny in my opinion, although some thought so. Now a days, with high energy electronic ignition systems I guess the "trickster" might suffer a heart attack!
The other popular one was in the fitting shop where there were several large metal trunks in which were kept the tools, files, hammers, soldering irons, etc These had loose filling tops - no hinges. there were also a number of mains gas powered "turbo" torches for brazing exercises. The "trick" was to use on of the torches to introduce gas into the trunk with the top just slightly moved to one side. Then, when you judged a goodly quantity of gas had been introduced, you replaced the lid, sparked up the torch and hovered the flame near the edge of the lid. If you'd got the right mix of air and gas in the trunk - and that was actually quite difficult as too little gas just produced a "wet phart" whereas too much gas made a flame all round the edge of the lid - get it right though and the gas/air mix in the trunk exploded sending the lid up to the roof! Not surprisingly, when it came back down, it often caused mayhem so was deeply frowned upon if you got caught. I though it was much more fun to place the rather large funnel we made as a test piece inverted on the bench, fill it with gas and then light the gas coming out of the end of the funnel. A flame would burn, like a big candle, until enough air had been dragged into the bottom between the bench and rim of the funnel to give an ignitable mix where upon the mix would explode and cause the funnel to jump into the air for about 5 or 6 feet. Much more fun and almost risk free.
