The expression "E ticket ride" comes from Disneyland. A long time ago Disneyland sold tickets designated A, B, C, D, and E. The A tickets where the cheapest and were for the least exciting rides. The B tickets costed slightly more and were for the slightly more exciting rides. The E ticket rides costed the most and were for the most exciting rides in the park.
Disneyland has since done away with the "ticket per ride" scheme and changed to the flat entrance fee scheme where all the rides are free once you've paid to get in.