I change mine more frequently than I display it, but it’s probably either from Firefly, Thomas Payne, or shooting related.
Behold -
Can’t decide if I want to change mine or not. It’s so very perfect to insert in a thread…about three times a year.
Here’s mine. It’s related to Lady Mary Lygon gaining a position at the British Museum Library, IIRC.
Currently mine is:
I was amused when someone quoted it back at me when I disagreed with him on a song he loved.
mine
Let’s see if I even have one set.
(How about that, I do! 
)
I steal the wit of other dopers and use it as my sig 
I keep forgetting I have one. I generally steal them from wittier Dopers.
Mine’s nothing special
I used to have this one, stolen from somewhere:
Jesus saves.
Buddha forgives.
Cthulhu thinks you’d make a good sandwich.
Mine.
When this board gets off the ground default signatures is one of the things we need. And avatars too.
I don’t even remember mine, so let’s learn together:
You’ve inspired me. I’ve finally added a sig.
Here’s mine. Quite appropriate.
Cite?
I’ve had the same one for 8 years. Maybe it’s time for something new?
mine
I change mine now and then.
I don’t use it much and the references are becoming dated, even if the sentiment hasn’t.
If I ever found a noble house (Duke of Toronto, anyone?) or at least have a coat of arms, mine will be my motto: