"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.

Running for exercise and picking up trash you find along the way. It's good for the body, mind, soul, and environment! Started in Sweden but is making its way to the U. S.