If you're too scared to tell them you're new to smoking it sounds like you're doing it just to fit in..

If I were you I'd tell them you've never smoked before, because no one hates anything more then someone who lies about it and is a total noob, "oh yeah I've smoked before" then you take 1 drag off their joint and you start coughin up a lung they'll know whats up and probably laugh at you and joke behind your back or something

If they won't let you smoke because you're new too it, they aren't really your friends and I would find someone else to smoke with who doesn't care how experienced you are.. and in all my days of blazing I've never seen people hate on someone because they're new to smoking. I personally love taking virgin lungs and I'm sure lots of other people do too but don't act like a retard and just chill and enjoy it, don't yell or talk about stupid shit just to seem like your high