I came across this sample sentence in Oxford Dictionary，under the entry "spook":
They spooked a couple of grizzly bears.
I consulted an Oxford dictionary of English-Chinese edition, and it translates the sentence into "They frightened two grizzly bears".
Maybe OK but I am still not fully convinced it means only two bears in the sentence. Does "a couple of bears" necessarily mean two, or have a meaning of more than two in most cases? As to in this sample sentence, I would prefer to interpret it as "they frightened some grizzly bears"(maybe they weren't quite sure of or didn't notice the exact number).