What is the meaning of [Men are known by the company they keep]

This is similar to Birds of a feather flock together.

Benjamin Hapgood Burt, the American lyricst, wrote the following delightful
jingle:

> One evening in October
> When I was far from sober,
> And dragging home a load with manly pride,
> My feet began to stutter,
> So I laid down in the gutter,
> And a pig came up and parked right by my side.
> Then I warbled, ‘Its’s fair weather
> When good fellows get together’,
> Till a lady passing by was heard to say :
> ‘You can tell a man who boozes
> By the company he chooses’.
> And the pig got up and slowly walked away.