A slight misunderstanding

Tonight, while L was in the bath tub (she likes me to sit there and talk to her):

L: Has anyone drown in a bathtub like this?
*Knowing that they have, because we've talked about it multiple times*
Me: Of course they have, honey. You know that.
L: But usually like babies or really old people?
Me: Usually, but anyone could slip in the tub and hit their heads just wrong and drown.
L: But usually that would be like babies or old titties?
Me: WHAT? Did you just say TITTIES?
L: Yeah, daddy says that.
Me: Daddy says "Old titties?"
L: Yeah, like when he's driving.
Me: Ooohhh...Do you mean "old BIDDIES?"
L: Yeah, biddies, that's it.
Me: *laughing*
L: What's titties?
Me: It's another word for breasts, but it's a rude word.
*and one of the few rude words NOT used around this house.
L: *laughs sheepishly*