The Meaning of Life, the Universe, and Everything.
If these people are really your friends, why are they sending you messages that you can't understand? They don't sound very friendly to me. Why can't you talk to them to find out why they are behaving like this?
This is probably a fun in-joke for them and they're just being silly, but it's not very nice of them to disclude you. Ask them about it and decide based off how they react, whether they really care about you in this context (of the gaming sessions) or not.