Nope. The LD50 of caffeine is between 150 and 200 mg/kg of body weight. And that’s only going to kill half the prior who take it. LD50 is also for instantaneous intake, consumption over time drastically increases it.

This is a really old test. There are forum posts of the same concept and some news articles with the test that are so old that they 404 now. An unshielded coat hanger is the most common. And yes, this is done frequently with analog signals. No, you can’t tell the difference.