As quoted above:

Sounds extremely sexual and kind of is.

Yes, in fact: in Irish-english, "the excitement," is a common way to describe the sexual act. This is best illustrated within the book Angela's Ashes by Frank McCourt. From Chapter 1 of Angela's Ashes:

A knee-trembler is the act itself done up against a wall, man and woman up on their toes, straining so hard their knees tremble with the excitement that's in it.