My arousal for any activity is something like (my own interest in the activity) x 2(my partner's interest in it). If either are zero then forget it, if both are high then ....YIPPPEEEEEEE!

...over a period of time having a great time with one particular activity will effect my own interest level so there is scope of for an exponentially orgasmic curve!
lol, love that orgasmic maths...guess my teachers should have used that as an example. *grins* And there's a lot of good stuff in that equation...