Lily Simpson has a good video essay on trans rep in HIMYM.

Verilybitchie also has great vids.
I can’t think of others off the top of my head right now, but I’ll send you a DM if I do! It’s likely that some of the big trans video essayists like Contrapoints and PhilosophyTube have vids to turn too

I believe you might be thinking of s1e19 - Mary the Paralegal. He tells Ted that Mary is an escort and when Ted protests Barney says “you think I’m gonna stick you with a toothless [t-slur] from the Port Authority?”