IMO there is little worse than under soaked/cooked beans. My wife, whom I love and hope never reads this post, used to make sweet and sour lentils. I never liked the flavor but to top it off she loved them. So much so she couldn't wait for them to cook all the way and would serve em up... er well, a little crunchy. Thankfully she is a much more accomplished cook than when we were first married.
If you forget to put the beans to soak the night before, you may use the method known as "power soak". Using the ratio 1 cup beans to 3 cups water, starting with cold water, bring the beans to a full boil, simmer 2 minutes, and kill the heat. Cover and let stand in the hot water for 1 to 2 hours. Then drain, and procede with cooking. Remember to go through the beans for dirt, debris and rocks. No matter how clean they look, I always find at least one pebble.