Throughout your life there will be a lot of things that happen to you that will challenge you. When you dont allow those things to affect you because you understand that it's not really a big deal what he/she is saying, is when you are said to have a strong frame. You'll get tested a lot by people who have strong frames. Dont worry about why they do this (most of the time they just do it cuz they assume you have a strong frame too (cuz having a strong frame is attractive. And attractive people like to hang out with attractive people). So they get weirded out if you react negatively to their test framing. Usually with comments like, "dude I was just fcking with you haha. Why are you so serious" it's just unattractive to hang with people you can't be yourself with to people with strong frames.
Calibration is just being aware of social context. When or when its appropriate to do/say certain things. As you get experience in social environments/hanging (and observing) with people with high social IQ as opposed to sitting at home reading about it, your intuition will get stronger and you'll just be a naturally calibrated person.