But it is you who seems to be doing most of the complaining. If you are not interested in the topic, then I suggest you stop reading it.
That was the rhyme that I was taught at school. I also remember a quite graphic BBC trade-test transmission that was repeatedly shown on BBC2 in the days before all-day TV - it taught the acronym "SIDE" (Switch-off, Isolate, Dump, Earth) to those working on high-voltage equipment. I knew that my father's work involved electricity, so I insisted he watch it (he was actually a telephone engineer, and never had anything to do with HV circuits).
1) with AC, the voltage alternates between positive and negative peaks. The stated voltage is the root-mean-square (or "average") of the alternating voltage. The peak voltage on a 240v AC supply is actually significantly higher than 240v. Whereas with a 240v DC supply you get 240v.
2) with DC, the current is constant, so causes the muscles to contract and stay contracted. So you may be unable to let go of whatever your are holding that is electrocuting you. With AC, the alternating positive and negative currents cause the muscles to go into spasm.
Perhaps the most significant factor in how severe a shock is, is how the supply is earthed, and how well you are connected to earth. With modern domestic mains supplies, the negative is usually earthed, so if you touch the live you will get the full 240v ac. However, the 110v supplies commonly used on building sites are centre-earthed, so although it is a 110v supply, the voltage to earth on either the live or neutral is only half that. The power supplies used on railway signalling circuits are supposed to be earth-free, so in theory (and I stress that bit) you shouldn't get any shock at all if you touch it. In practice, however, no supply is ever truly earth-free.
During my railway career, it was quite common to accidentally touch live 110v ac signalling circuits as the terminals carrying 110v ac were not covered. Depending on how earth-free the supply was, the shock was relatively benign. In fact, we would deliberately touch 110v terminals when fault-finding as a quick and easy way of seeing if the circuit were live or not. Whereas I have known someone receive a very nasty jolt from a 12v dc circuit.