"HEE HEE PET PET" is the near-incoherent inner
babble of a person who is engaging in pleasurable physical activity (petting
) with one of their chosen gender, more than likely
for the first time
in a long time
; this can refer not only to the exclamation but to the activity itself.
Glenda found herself somewhat dazed as Marshall
kissed her, the words "HEE HEE PET PET!" running through her sex-starved mind.