An expression used to describe an individual who through sloth-like behaviour causes others around him or her to be late for any event.
The term is often used by students at college or university (UK) and is sometimes used to refer to an individual who has been annoying, retarded, or been witnessed doing something of unquestionable stupidity.
"What a tool, that guy is an actual train delay."
"Late again, that Brannan is an actual train delay..."
"If Sarah doesn't stop pissing about we'll miss the start... AN ACTUAL TRAIN DELAY!"