Some other community members have picked out good introductory episodes that don't have too many in-jokes, especially because with all podcasts they get better as they go on and so the earlier episodes while not bad are not as good as the current stuff. However, my suggestion would still be to start at the beginning and work from there. It's not the sort of podcast you have to stay up to date on or else you'll miss out, so just take your time with it, let it fill in the lulls between your other podcasts' releases, and you'll catch up in no time!