1
general::
Also, going on for. Approaching, especially an age or time. For example, She's twelve, going on thirteen, or It's going on for midnight. The first term dates from the late 1500s, the variant from the mid1800s. Also see GO ON.
American Heritage Idioms
2
general::
Phrase(s): going on
happening; occurring. • What is going on here? • Something is going on in the center of town. Can you hear the sirens?
McGrawhill's American Idioms And Phrasal Verbs