Bungee jumping is the activity of jumping from a high place while secured by a long rubber band tied around the ankles. To be suspended means to be supported by attachment from above, to be hanging. "Suspended" can refer to being prohibited from a place. So, if someone is suspended from school, then they are prohibited from going to school for however long they were told they must stay away. This joke is playing on the word "suspended" and its different uses. 
Skipping school to bungee jump will get you suspended .