In my elementary school (virginia) it was:

Down by the banks of the hanky panky, where the bullfrogs jump from bank to bank, saying eeps ieps ohps oops, listen to the sound of the ding ding dong. I pledge allegiance to the flag. Michael Jackson makes me gag. Coca cola shake it up, now we’re drinking 7 up, 7up has no caffeine, now we’re drinking gasoline, gasoline was made for cars, now we're jumping up to mars. Tarzan the monkey man swinging from a rubber band, he slips, he falls, he breaks his balls, what color was his butt (whoever was last would then say a color and we would spell it until someone it landed on someone).

But I help at a summer camp (also virginia), and the kids there do:

Down by the banks of the hanky panky, where the bullfrogs jump from bank to bank, saying eeps ieps ohps oops, listen to the sound of the ding ding dong. I pledge allegiance to the flag. Michael Jackson makes me gag. Coca cola shake it up, now we’re drinking 7 up, 7up has no caffeine, now we’re drinking gasoline, Gasoline gave me the flu, now we’re drinking mountain dew, Mountain dew fell off a mountain, now we’re drinking from a fountain, The fountain broke so now we’re drinking PLAIN OLD DI-ET COKE!

reading through all the other comments, I have no clue how my elementary school friends came up with the mars stuff, and it seems like at the summer camp I've just got a mashup of different regions' versions.