to fear losing just a little bit of control.Talking about being high, or simply talking with people who are high, can affect you. We can mirror the people around us in surprising ways, and we can "psych ourselves out," so to speak.
As for absorbing the marijuana through second-hand smoke, being around high potency marijuana smoke in an area without ventilation can cause you to absorb some. If you don't want to absorb any, ventilate the room or have your friends blow smoke outside.
If you live in an area where marijuana is illegal, or if you just don't like the smell lingering in your house or traveling towards your neighbors, find something to blow the smoke into.
Whether or not you get detached is somewhat in your control, and there's no reason to fear losing just a little bit of control. That being said, it's totally reasonable to ask your friends to blow outside or into something to catch the smoke.