Did you ever lick a metal pencil sharpener when you were a kid and wondered why it tasted funny but only in certain parts? Finally - here is the answer.
"I know the answer and actually it was much better on pencil sharpeners: it is bimetallic ELECTROLYSIS of the TONGUE… the sharpener blade is one alloy and the body (or the screws) are another, and when you place the two metals in a conducting liquid viz spit, the electrons travel from the cathode to the anode (or vice versa, or anyway something like that: google for correct direction) => the fizziness is CURRENT FLOW hurrah!!
why it happened on those tabs i don’t know… maybe they were bimetallic too, but i can’t see how: it was less powerful (actually possibly doing a proustian madeleine here: viz the TASTE of the tabs was the same as the TASTE of one of the metals in a pencil sharpener, but the fizziness was only on the pencil sharpener, but my memory is conflating and tranferring!!)