Boys get erections and masturbate. There's no female involvement, unless you count the surprised faces of the girls who'd been drawing a boy in life class. No plot. No dialogue. Just lots of little scenarios and different settings.
Uraukaze, Hamakaze, Shokaze in Conqueror
Episodes: 1 x 4 minutes
Keep watching: n/a
One-line summary: dirty CGI music video
It's another Conqueror video, but there are three dancers to compensate for this and they have strong choreography with big arm movements. It looks quite good.
The dancers are ship-girls from KanColle, incidentally. No sex, just stripping.