"Teacher's Pet" joke

On the last day of kindergarten, all the children brought presents for their teacher.
The florist's son handed the teacher a gift. She shook it, held it up and said "I bet I know what it is — it's some flowers!"
"That's right!" shouted the little boy.
Then the candy store owner's daughter handed the teacher a gift. She held it up, shook it and said "I bet I know what it is — it's a box of candy!"
"That's right!" shouted the little girl.
The next gift was from the liquor store owner's son. The teacher held it up and saw that it was leaking. She touched a drop with her finger and tasted it.
"Is it wine?" she asked.
"No," the boy answered. The teacher touched another drop to her tongue.
"Is it champagne?" she asked.
"No," the boy answered.
''What is it?"
"A puppy!"