Zac Efron and Vanessa Hudgens are making it clear that they're a couple (as if we didn't know!). Word on the 'High School Musical 3' set is that the lovebirds were all about PDA last week.

E! Online reports that during a 15-hour shoot on Tuesday, sources say Zac and Vanessa were not only giggling and holding hands between takes but they were sprawled out "like lovers on a picnic."

"When they're not needed on set, they're on each other's laps," says a set source. Ahhh, to be young and in love and working on the most anticipated teen sequel -- together.