Heidi Klum -- Nightclub Face Sucking ... With 27-Year-Old BF [PHOTOS]

Heidi Klum's not afraid of a little PDA -- donating some fresh spit to her young art dealer boyfriend Saturday night at a Hollywood nightclub ... in the middle of the crowded dance floor ... and TMZ has obtained photos.

The DFMO (dance floor make out) went down at 1 OAK -- Klum grabbed 27-year-old Vito Schnabel's face and passionately kissed him in front of everyone.

She looks really into it. Vito looks like a prom virgin.

Then again, he's the one dating a supermodel.