My DF was just over for a visit. During the chat we were talking about a table he'd had in his house since I was a kid, that he'd given me, and I'd given back during renovations and now I have no room for. I told him I'd said as much to my brother who had joked "I used to want that but not now - I don't want your sloppy seconds!" When DF left OH laughed and said "I can't believe you used that expression to your Dad! It means shagging someone straight after someone else has." And then went on Urban Dictionary to prove it.
I've never heard it like that before - I know it can mean dating a person someone else has, but I think of it more in a general sense like "Do you want this top I don't want?" "No I don't want your sloppy seconds" and only in a jokey sense. What do you take the expression to mean? Was I a moron or do I tell OH to get his head out of the gutter!