The last thing you should do when you are watching a theatre performance is doze off; and more so when you are watching theatre for the first time, and when you have told your friends that you are more than interested in watching theatre atleast once, and when the same very friends are sitting next to you,and when there's a probability that the moment you doze off, you are going to be laughed at for the next two days or three or maybe four days atleast.

Assuming that the play is very very boring,(which most of the times is not the case though), there are tactics that you should employ to keep yourself awake...
Ahem... ahem...but these tactics come after you have exhausted the options of having coffee and popcorn, and yeah.. even throwing popcorns at people.

So option 1, a good idea would be to look to your right side, where your friends are sitting, catch them yawning(make them yawn if you cant catch them yawning, otherwise)and scream with surprise and sarcasm, "someone prefers to sleep in air conditioned theatres and halls... huh!!" And this should leave them embarrassed enough to not even look at you throughout the rest of the performance, for they are gonna be busy adjusting their eyes to the widest size they can open.

Another good option, option 2, is to get up , take a walk down the aisle, and give a missed call to one of your friends, then go back and tell them very very seriously that cellphones are required to be switched off through the performance, and that they should respect the artiste on the stage. And, nobody's going to ever doubt the point that there could be any other soul, more interested or more engrossed in the performance than you were.

Another option, the best one, as I see it is to tilt your head to one side, adjust the angle nicely so that you face towards the stage, lean on your arm your back towards your friends, and peacefully go to sleep. And, in case they happen to call out your name in the middle of the show, let them assume that you are just too busy and too engrossed to even listen to them...
But do make sure, you do get up in time to give a big round of applause to the artists, once the performance is over. Rather, a standing ovation is what I would say....

Cheers!!