Scrap off the stem or the cap of the avocado. If you see a green creamy texture, rest assured the fruit is ripe. If you are unable to peel it or mash it, the fruit is not ripe. Keep in mind that extra ripe avocados taste bitter and should not be consumed. If you want an avocado right away, look for a dark skinned one with little flecks of green. Very black ones are past ripe and taste bad.