Call Me Dave

Yesterday I took the kids to an activity for our homeschool group. I let the four older ones go in while the three little ones hung out with me in the van in the parking lot.
A man started his pickup and pulled out of the space next to us.
Christopher commented that his pickup sounded just like Daddy's (a diesel).
Elijah thought he said it was Daddy.
Christopher said no, it wasn't Daddy 'cause his name wasn't Dennis.
I said "that's right--(then to check again) 'cause what's Daddy's name?"
Christopher said, "Dennis."
I asked if he knew mommy's name.
His reply: "I dunno, um, Dave?"