meanings

[lingchen]

Hi Teacher,

I have difficulty understanding the parts in red. Would you please give me a hand?

1.Danny’s was an S-and-M-stand and model-bar.
The younger men would assume poses that made them appear as attractive
as possible, while the other men-the buyer-would look them over and make
their selections. … There were never any fights in them, for
the most of the customers had capped teeth, and they
could not afford to chance having them knocked out.

2. When Robert reached the next corner, he noticed that it was a one-way
street. He turned into it, going against the heavy traffic.
3. The envelope was sealed and addressed simply: ”Commander Robert
Bellamy.” He fingered it, feeling for plastique or any metal inside. He
opened it carefully. Inside was a printed card advertising an Italian
restaurant. It was innocent enough. Except for his
name on the envelope.

Thanks a lot.

[Tdol]

S&M = sado-masochism, so presumably, they modelled the clothes. People with capped teeth don't want them broken, so they stay out of fights.

Going against the flow of the traffic

Innocent = harmless