My students are not the best inferrers

My TOEFL students REALLY struggled with inference in Wednesdays lesson so I gave them a quick worksheet with simple sentences and then asked them to infer. 

•  Example: "Oh honey you don't have to get be anything for my birthday, just being with you is enough. I am going to go to the store now. I hope that my purse doesn't fall apart on the way there. It is so old!"
• Inference: The person would like a purse for their birthday.

They struggled a little, but they improved a lot! They helped each other and when they were stuck I asked questions:

• Example: An older man is running behind a school bus waving a child's lunch box in the air

Me: When do you run?
Students: To stay fit. Because you are late. To get away from someone etc.
Me: Is the man working out?
Students: No, he has a lunch box.
Me: Why would he run with a lunch box?
Students: He needs to give it to someone
Me: Whom might he need to give it to?

• Inference: The man's child is on the bus and has forgotten his lunch.

One of the statements was:  You are giving a presentation for a large audience, and you notice people are laughing quietly at you while they point to the region below your belt.

My students had NO idea. I even had a volunteer come to the front of the class and stand there while I pointed at his general groin area. They were clueless! Once I explained it they all understood, but I was amazed no one got it.

I talked to my boss and a few other people and they got it right away... I wonder why they had so much trouble.

Do you get it?