A slang term from the psychiatric condition known as "Knismolagnia", in which a person derives sexual gratification from tickling or being tickled. Comes from the Greek word "Knismos" (tickle) and "Lagnia" the Greek word for lust.
Girl #1: Oooh he's cute!
Girl #2: Yeah but you better be cool with gettin your giggle on; I heard he's a total knismo.
May also be combined with podiaphile if the feet are a particular tickling interest: Podiaphillic Knismo