I a fleeting scene, a man uses a pen to playfully paint an "f-hole" on a woman buttocks suggesting similarity to a cello.
A woman's buttocks are visible in a thong-type undergarment. Scantily dressed prostitutes:A woman's buttocks are visible in a thong-type undergarment. another shows a barely discernible glimpse of a breast thru a sheer upper garment, and is fleeting and barely visible.
Prostitution and the main character's presence in a brothel is implied through choice words and commonly-understood images but done so in a "soft" manner and not spoken of directly.
A man displays postcards, of nude women, that he has for sale.
One scene where hints are given as to the meaning of a song being about an erection, a woman lets her hand run down the front of a man's trousers. As with the other scenes it is not overt or drawn out.
Except for "going up stairs" with a prostitute, Sex is not discussed, or shown in any maner.
(It appears like all/some of the quick nudity was just over the line for R-rating.)