To sneak away from a group (usually at night), to commence a crazy make-out session. 'Stargazing' usually occurs with another individual, though solo macking sessions have been known to occur. These individual stargazing excursions are generally discouraged and seen as anti-social.
Mary: "Chrissy where did you go last night, we were waiting for you."
Chrissy: "Oh, I was stargazing"
Mary: "...with B-Shay?"
Chrissy: "No, by myself"