A father and his 6-year-old son are walking down the street, and they come across two dogs having sex.
The boy is shocked by what he sees and asks his father "Daddy, what are they doing?".
The father, not wanting to lie to his son, says "they're just making a puppy."
"OK" says the son, and the father is relieved that he doesn't probe further.
The next day, the son bursts into his parents' room and sees them having sex.
The father jumps up and quickly covers himself.
Knowing he's in for an interesting talk, walks downstairs with him and they sit at the dining room table.
His son asks him "Daddy, what were you and mommy doing?".
Again, wanting to be honest with his son, he says "me and mommy were making a baby."
His son pauses for a moment, thinking, and then replies "flip mommy over, I want a puppy!".