Occasionally I get asked to play at a piano but I just tell them I don't play piano. It would only make me look like I don't know what I'm doing! About the most I'll do is Happy Birthday on one.
I actually never do jam sessions or freebies "for the fun of it". I'd come closer to picking up a guitar and picking something and that would be bad now too.
If I'm asked to do something for a good cause or good friend and I want to do it, yes, I take a keyboard and mic. You wouldn't believe how many parties I've been invited to and they casually throw in "by the way bring your gear and play for us a while." On second thought you probably would believe it!
I would never invite an MD over for dinner and say, "by the way bring your stethoscope and blood pressure cuff."
Don't get me wrong I know it's different if you aren't doing this stuff for a living, and it's a hobby that you are good at doing.
If it's fun for you, knock yourself out!
DonM