Q: Why was the baby strawberry crying? A: Because her parents were in a jam!\nWhat do you think is the punchline of the above joke?
Explanation: Jam is a type of food that is typically made of fruit. Jam is usually spread on another food like bread or toast (like the way butter is spread on bread or toast). If you use strawberries to make jam, you have made strawberry jam. Mmmm! I like it.
To be in a jam is an idiom that means to be in a difficult situation, to have a problem.
This joke is funny because it plays with meanings of the word jam. Yes, it might make you cry if your parents were in a jam (in a difficult situation), especially if you are a strawberry!
The word jam is also used when musicians play together like in the video below. A jam session is usually informal and may involve improvisation.