We were definitely not a pardon household.
I tend to say, "what did you say?" or "Sorry, I didn't catch that," or "Can you repeat that please?" (Half the time, what I really want to say, "Will you put the fucking speaker near your mouth and speak up! I expect you to concentrate when you're on my conference call!" Obviously, I never had, but god, some of them mumble away in the distance!) The majority of my colleagues are in different countries and English isn't their first language, so I do think it's important to try and speak clearly - I try to avoid slang, dialect and too much Dorset accent, and I think as I usually communicate with them by phone, "Can you repeat that please?" is usually clearest, sometimes accompanied by, "You're really quiet, are you near the mic?"
I do also sometimes catch myself saying, "say again." I know I picked this up from having to use a radio when camping out and calling home to base camp in the past. I annoy myself every time I hear myself say it.
I am also trying to stop myself saying "sorry" when I don't hear, particularly if it's them mumbling that's the problem. Although I think it's okay when it's, "Sorry, please can you speak in my left ear and speak up, I've had a bit of an ear infection, and I'm half-deaf," - because that is me at fault. A couple of my German colleagues delight in pointing out how British I am, apologising all the time. "Why are you saying sorry, when it's not your fault?" Mind you, on bad days, I do have a tendency to apologise for my entire existence.
Sofa, napkins, loo/bog - although toilets in public place, such as shopping malls, restaurants, train stations, etc. And also mirror, not looking-glass (but I was brought up to be aware of the Mitfords and U/non-U.)
Whichever words are used, usually you can tell by the tone of voice whether someone's actually intending to be rude or not.