I play poker online and I've never heard this phrase being used. It makes no sense to me. I googled and found this answer on reddit: "The WSOP app added this poker club feature where essentially the more you play the higher club you are in. Ever since they did that they added those club phrases. They are basically nonsense and not actual poker terms." https://www.reddit.com/r/poker/comments/9g07fx/clubbing_up/ So, it seems that phrases like "club on" and "clubbing up" are nonsense phrases which don't mean much of anything, derived from a feature of the WSOP app.