You Know You're A Davidson . . .

. . . if, at a wedding in the family, you look in the guestbook and see someone has signed it as

Gimli son of Gloin

and in response someone else has signed as

Frodo son of Drogo

and the only reason you don't sign in kind is because your wife is watching, only later to learn she wanted to sign with Gandalf's whole name, but couldn't remember it in time to do so.