They had just married and wanted to have kids. But for some unlucky reason, they had trouble conceiving.
Few months go past and finally! The wife is pregnant. The couple is super excited and happy as ever. The day comes when the wife is giving birth, and out comes a head... just a head. The baby was breathing and crying, but the doctors could not explain why he didn't have a body.
As sad as this was, it didn't phase the parents. They gave him a beautiful home, a great education, and a wonderful life. They did their best to not let their child feel disadvantaged, and it worked, because the child grew up to be a happy and successful student.
On the kid's 18th birthday, his father and some family friends took him out to have a beer. This was his first ever beer, and his father felt like he deserved it. Using a straw, the kid took his first ever sip of beer, and all of a sudden, his body stretches out! And some arms! And legs too!
He couldn't believe it, no one did. The kid became ecstatic and began rejoicing. He got up, and ran out of the pub to celebrate and spread the news to the other townsfolk, and WHAM! he gets hit by a bus.
His father looks from the window, and says "Well, he should've quit while he was ahead"