DD did this too (minus the fountain part) for a while. I have no clue what the fascination was. She didn't do it as much if the liquid was really cold though. We limited sippy time to in the high chair only and changed a lot of shirts. We also took the cup away if it was clear she wasn't drinking at all. She quit after a few months.
Melissa-Wife, mother to DS 4/02 and DD 4/07, DS 7/08
ISO: my lost shaker of salt