If someone gets hurt, the vehicle that takes them to the hospital is the "amba-lamps". The life flight vehicle is a "hoppa-cow-ah".
My kid misunderstood "On your mark, get set" so he said "On your market, get started."
The things on chimneys to keep out squirrels and raccoons are "Santa Caps" used by families who don't celebrate Christmas to signal Santa to pass on by.
One night my husband was all stressed and we were trying to get our son calmed down for bed. Our son called out, "RAX (for "relax") Daddy!" We still say this when my husband is too revved up.
Our son was really late in the potty training department. I finally told my very modest husband he absolutely HAD to take our child into the bathroom to show him how big boys pee. From behind the closed door, I heard "WOW! A WATERFALL!" We still quote that one when we're on a nature walk and find a little waterfall.
Be sure to write all these things down in a journal or a baby book - they're really fun to read years from now and to share with your child!