Mr. and Mrs. Leopold

"Hello, Mr. Leopold", Dominic greeted his Daddy.

"Stop that, Mrs. Leopold", Pia said to his Mommy.

They've taken to calling us Mr. and Mrs. Leopold.

Except that we don't know where they get picked up the name "Leopold".  It's not our name.

Until we solve the mystery, we remain clueless why we are suddenly "Mr. and Mrs. Leopold"