What's the difference between marbles and babies?
You can't load marbles onto a truck with a pitchfork.
Actually, on the classic line of babies...
In some peaceful surburbia, a midwife is going to visit a newborn baby. This midwife has been so impressed with the husband, he has been possibly the best husband ever. He's supported his wife through the pregnancy, made her feel loved and cherished, he was there holding her hand through every step of the birth, he cut the umblical cord and proudly carried the cot home to an already fully decorated nursery room, painted in a beautiful blue with a little border of footballs on the day they found out it was a boy.
She knocks on the door of the house, and the mother opens the door. "Come in" she says, "he's just upstairs bathing the baby." Aw! Of course he is. Perfect.
The midwife creeps up the stairs, not wanting to overly disturb this bonding moment. She peeps in, and does a double take...
The father has his two fingers up the baby's nose, and is using them to hold the poor child while he swishes him around in the water.
"Stop! Stop!" the midwife yells, "you don't bath a baby like that!"
The Dad looks up, puzzled, and says "You do when the water's this hot..."

And finally, my current favourite joke, gleaned from the book "Rule of Four"...
A man walks into a bar, stark naked and with a duck on his head. The barman says, "hmm... there's something different about you tonight, George."
The duck says "Harry, you wouldn't believe me if I told you."