Do not stick guns in your pants without holsters. There are several reasons why you should not do this. I will give a short list:
1. The weapon will fall out in a fight. In a fight where will you be? That's right--the ground. I'm sure some gun rag has said that this is a brillant idea, but it is hard to fight back without your pistol ("King's X!"). Another example is the hurried, fumbled draw. As you are running for something solid, you, not being the Selous Scout that everyone else is, may knock your pistol down your pants. P.J. O'Rourke writes about such as incident when his collective was invaded by the Balto Cong and the undercover mall ninja knocked his .45 down his bell bottoms.
2. The holster can help you in one-handed drills. Even if you do put a big, old (a little Southern lingo) scar on your rig (like I have done), a holster helps to clear Type II mals. Having a holster also helps in reloading one-handed.
3. The holster helps you conceal it by bringing tight against you.
4. A good holster helps you retain the pistol.
Putting the pistol in your pocket does not work for me. It may depend on your hand size, but it is slower as it is more difficult to obtain a proper grip in the pocket.
Buy a good holster.