b && c in ruby

b && c

[true, false, 1223, nil].each do |b|
  [true, false, 5555, nil].each do |c|
    a = b && c              
    puts "#{b} && #{c} = #{a}"
  end
end

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
true && true = true
true && false = false
true && 5555 = 5555
true &&  = 
false && true = false
false && false = false
false && 5555 = false
false &&  = false
1223 && true = true
1223 && false = false
1223 && 5555 = 5555
1223 &&  = 
 && true = 
 && false = 
 && 5555 = 
 &&  = 

For what it's worth, the context I saw it in was:
some_id = params[:foo] && params[:foo][:bar_id]
...
SomeModel.find_by_id(some_id)

which is equivalent to:
some_id = params[:foo][:bar_id] if params[:foo]

In this particular case, the usage was, only assign to the variable if the hash exists. And then go use whatever that value was somewhere else. On reading it, I thought that line -- some_id = params[:foo] && params[:foo][:bar_id] --
was assigning a boolean to some_id, and so was confused by the later usage. Maybe it's common elsewhere, but I haven't seen it before.