Loser?

I'm still working at the portrait studio on weekends... at least through Christmas.
So I was there today - and got to photograph a fun family - Mom, Dad, their 3 grown daughters and their significant others and their kids.

I like to know how to group people, so as I'm getting to know a family of this size I like to ask who belongs to whom. (is that the right grammar?)

They pointed out: "Al is Abby's husband and both kids are theirs. Sarah is dating Sam, and Elly is the only single one."

I smiled at her and said, "Good for you!" sort of to squelch the sting of her dad pointing out her glaring difference in the family.
As Elly and I exchanged a little high five, her dad leaned in and joked, "Loser!"

"Hey hey HEY!" I said, "That only means she hasn't made any big mistakes!"

She smiled at my support, and the jabs the family was gearing up - petered out.

Man, people are so freakin' dense!!!