The other user answered it correctly, but I do this whenever I make a small bet. I am not talking about Las Vegas mega million betting, but just simple "if this happens, you owe me $--" After I win the bet, the other person challenges me, and asks if I want to go double or nothing. This is where I can choose to keep the bird in the hand, or go for two in the bush. This is just a small example of what I think when I hear this idiom.