Zac Efron was spotted in London leaving GMTV studios after promoting his new film ‘Me And Orson Welles.’

Zac left through the rear of the studio — his favorite location on a man — in the rain, but a few lucky fans stalked him hard enough that he greeted them and signed autographs.

But get this, as Zac turned to walk back towards his Limo, he realized that he still had one of the fan’s pen and threw it while doing a Spiderman pose — WTF?!

Doesn’t Spiderman do that weird pose where his butt is also up in the air, or maybe that’s just my specialty? EEK, so excited that our baby-daddy is back!