Treading on eggshells

Li: Hello and welcome to The English We Speak. I'm Li and with me is Rob. Hi Rob.
Rob: Hi Li. It looks like you've been busy.
Li: I've just picked up some groceries from the local shop, you know—milk, eggs, bread, flour—I'm going to make a cake.
Rob: Oh good. So how was Mr Brown, the shopkeeper? Hasn't he just split up with his wife?
Li: He has. It was tricky in the shop. I didn't want to say anything to him just in case I mentioned his wife. I only said: "Good morning", and he just said: "Is it?"
Rob: Hmm, it sounds like you've been treading on eggshells.
Li: Oh no, the shop was very clean, nothing on the floor—I don't really think he's the sort of person to throw food around!
Rob: No Li—I mean you were trying very hard not to upset him—that's what treading on eggshells means.
Li: Oh! So it's about being nice—it's about being sensitive to the situation?
Rob: Yes.
Li: Well, I was very sensitive. But what have eggshells got to do with it?
Rob: Well, if there were eggshells on the floor literally you would have to be very careful where you put your feet!
Li: OK, but this phrase means you are being careful about what you say. Let's hear some examples:
I had to be so careful with what I said to my ex-girlfriend. The smallest thing made her angry: it was like treading on eggshells.
Ever since my argument with my neighbour about parking, I feel like I've been treading on eggshells.
Li: So, treading on eggshells can be awkward because you don't know what to say and you don't want to offend someone. So Rob, what should I have said to Mr Brown?
Rob: You could have said 'plenty more fish in the sea!'
Li: What?!
Rob: Or ... 'I didn't like her much anyway'?
Li: Rob, I think that's the opposite of treading on eggshells.
Rob: Really? Anyway let me help you with your shopping ... oops (Rob drops the eggs!).
Li: Rob! You've dropped the eggs all over my kitchen floor.
Rob: Now you really will be walking on eggshells!
Li: That's not funny.
Rob: I didn't like your cakes much anyway.
Both: Bye.