Taking a day off from your adult responsibilities to relax and reconnect with your inner child by watching movies / television ads from your childhood, eating the same food etc.

Not yet sanctioned by modern psychology

A reference to the movie "Ferris Bueller's Day Off"

Used as filler when nobody responds to a question or statement.

No one is there. A constant trying to contact a person with zero replies back.

someone, usually a friend that misses out on class ocasionally.

From the title character in the classic movie "Ferris Bueller's Day Off".

To take time off work, in an unauthorised and if possible un-noticed way.

Most commonly to leave work for lunch with a few close friends and not come back.

No ones there. Alone. Talking to a group of people when you know none of them what to volunteer for what you’re asking.

When wondering where a student may consciously be (daydreaming of a teacher's nicely rotund ass, or brain dead as to too much knowledge being packed in at once) prompting if they are indeed present, this may be said.