Two male characters were seen (implied) that their genitals were always "standing at attention".
Two male characters were implied to be masturbating (sitting down behind their desks) in a room full of male and female.
A male character had sexual fantasy of a female character while masturbating.
The Chinese Mandarin slang for masturbating ("j***ing off") was used several times.
A male character appeared several times seemingly butt-naked. We only see his back (from top to toe), hence we see a bare buttock. Another male character was implied to be butt-naked as well, but we do not see his bare back-side.
Two scenes of several males showering in shower room, all with individual stalls and curtain across. We only see the legs area. There was a scene which showed a stall with 2 pairs of legs instead of 1 pair, and another scene which showed 3 pairs of legs.
No frontal nudity in the whole movie.