a term used to describe an enormous task or group of jobs that need completing. The tasks must include physical exertion, thought and take a lot of effort, just like training an elephant.
Different coloured elephants can be used to describe the difficulty of a task along the colour spectrum; red/orange elephants are easiest, blue/purple elephants the most difficult
Q: Are you coming out tonight?
A: Can't, I've got to train an elephant
Q: What are you up to this weekend
A: I'm doing some orange elephant training
Q: That'll only take an hour, come to the bar
Q: How's your essay
A: Harder then training a blue elephant