The Freight Train Effect is what happens when one consumes a substantial quantity of alcohol in a very short period of time, preferebly on an empty stomach. The effect is named so because the drinker becomes suddenly and completely wasted, as if they were hit like a freight train. The hangover often hits with similar effects.
"Man, I just took 6 shots and I haven't eaten anything all day."
"oh shit, that stuffs gonna hit you like a freight train, total freight train effect"
"....(drinker passed out on floor)