The trains that return to the depot at the end of the night without making any stops to pick up passengers.
I thought there weren't any trains left at this hour, but we're in luck-- here comes one now! Oh fuck it's just the midnight express, god dammit!
by Douglas Young January 26, 2008
The Midnight Express is a descriptive term to describe the act of taking a late night bowel movement that is coupled with a raunchy smelling odor that slowly seeps outwards from the bathroom and typically results in waking up all occupants of a household.

The Midnight Express though rare, typically originates from a steady diet of junk food, taco bell, and other bowel stimulating foods. Such foods by themselves are relatively harmless however under special circumstances these foods will cascade together in an order that creates a harden plug with a toxic gaseous liquid behind it.

Once such circumstances exist, typically the “Train Driver” -the person who performs the midnight express- will experience “whistle blowing” –also called flatulence- ranging from one to three days until the plug reaches the end of its journey, which in the case of the midnight express will be between the hours of 11pm to 3am. This critical point is also referred to as the “train leaving the station” or the “All Aboard Call”.

Sometimes this All aboard Call is mistaken by the Train Driver as just another Whistle Blow which to there surprise results in either a mad dash to the bathroom or squashing allover themselves rather than the nice casual stroll. This loud trotting sound only adds effect to the Midnight Express imagery and the wet Whistle Blow is the tail-tail sign that the Midnight express is about to roll thru.
I was peacefully dreaming until my roommate took a midnight express which woke me up and left me gasping for air.

After I took a midnight express it took 5 days to get the smell out of the house.
by Fleet_Admiral July 19, 2006
1. Movie directed by Alan Parker in 1978, loosely speaking about the real-life experiences of young American hashish smuggler Billy Hayes in a Turkish prison. Starring Brad Davis and John Hurt. Script by Oliver Stone.

2. To escape from prison or some other aversive situation. Reference taken from Parker's movie.
Midnight Express had six nominations for Academy Awards and won two of them.

I had to catch the midnight express out of boarding school.
by Fearman May 24, 2008
Attempting anal intercourse with your sleeping partner.

Note - This can performed at anytime of the day, but has more signifance when perfomed in the mignight hour.

Reference - Midnight Express (1978) - American college student sentenced to life in jail in Turkey for trying to smuggle Hashish. During his time in prison is repeatedly sodomized by jailers.
I tried to catch the Midnight Express, but got a slap across the face instead.
by Bruno Cosentino May 19, 2006