We had been talking about "save-the-dates", which (as you may or may not know-- I didn't know until I heard the term on the US version of The Office) are a kind of pre-invitation that comes before a wedding invitation. We were pondering over this concept, which seems a bit odd to both of us. Yesterday (for a bit of background information) we had been deploring the modern proliferation of acronyms.
My Father (completely innocently): "Of course, they'll probably be calling them STD's soon."
Me (smiling): "I don't think that's going to happen".
My Father: "Why not?"
Me: "Well, STD already means something else."
My Father, after pondering for a few moments: "Oh....single trunk dialling?"
Can you imagine? "Hey, Jill, did you get the STD yet? I thought I gave it to you at the party! Never mind, I'll give it to you later."