Having a succession of waves or curves.
Kiko: What is with you, tonight? Must be one of those high testosterone nights!
Tommy: Are you saying my testosterone level rises and falls like a sinusoidal wave?
Kiko: *fanfare* Acquired new key term: Sinusoidal! YESSS!
Tommy: You didn't know the term SINUSOIDAL? I'm disappointed!
Kiko: I thought you had misspelled/messed-up "sinuous."
Tommy: Damn escrillo!