Patrick Schwarzenegger -- Sad Sack in Malibu

Patrick Schwarzenegger looked the worse for wear in Malibu Saturday.

Arnold's son returned from Spring Break in Cabo, where he got chummy with a couple of chicks, apparently much to the dismay of Miley Cyrus.

One girl was his best friend's girlfriend, and the other was his ex, but it was all out in the open and certainly looked innocent enough ... to some, but not MIley.

Patrick and a few buds hit up a Malibu restaurant, where he hooded up, looking pretty pensive.

Patrick is a student at USC. Miley didn't go to college. Is this just part of a ritual that Miley doesn't understand, or does she have a point?