Of the 60 some-odd films Warhol made between 1963 and 1968, none is more frustrating or satisfying than Blow Job, probably because the whole thing feels like a tease. Then again, 35 minutes of face time with a guy who's getting serviced tend to have that effect. Stark, sleek, and slowed down, this little flick — the first in a monthlong series of rarely screened gems — shows that there's more to arousal than a mere money shot.