One of my friends got a speeding ticket and was attending a defensive-driving course to have points erased from her license. 

The instructor, a police officer, emphasized that being on time was crucial, and that the classroom doors would be locked when each session began.

Just after one class started, someone knocked on the locked door.  The officer opened it and asked, "Why are you late?"

The student replied, "I was trying not to get another ticket."  The officer let him in.