use "his" or "her" rather than "their"
Currently it says "Tasmydian set their epic win" in my activity log. It should probably read "his or her" rather than "their". I can't remember if I set my gender in my profile or not, if so you could use that info to make it "his".
Cheers, love SuperBetter!
Personally I like seeing "their" -- besides being less wordy than "his or her", it's inclusive of those of us who don't like being referred to with binary gender pronouns! No doubt someday there will be an option to specify your gender and have your activity feed use the relevant pronouns, but in the meantime, they/them/their is IMO the obvious best choice.
Justin White commented
I agree as an 'optional' feature if you select a gender in your profile. Some people would prefer the gender neutral option for additional anonymity (even though AFAIK only allies can see your activity - new users may not know that and there are people who might think that's more information than they'd care to give out.)