I could smoke the weed. It could be fun, and they would think I was cool... but it could impair my judgment, making me do something risky during the movie. Also, if some smelled it I could get in trouble with the law!
I could choose not to smoke, but still go to the movie with my friends. This way, I could avoid the risks but still have fun at the movie. On the other hand, I will feel left out and my friends might think I'm a loser.
Or, I could choose not to smoke, and convince my friends not to smoke either. This way, my friends and I could avoid the dangerous effects of weed, and I won't feel left out. But, we won't have fun and get high.