What exactly does "shampoo effect" mean?

Yesterday I told Metts that if I had one glass of booze I'd be drunk... You know, the "shampoo effect".. that phenomena which happens after you drink too much one day so you easily get drunk the next day. Then we got to talking about the Shampoo Effect and where that phrase come from slash meant as we didn't really understand why all of us said it.. So, I Googled it this morning and found the following definition on  Urban Dictionary:

A residual drug or alcohol phenomonon in which, during a period after a heavy binge, only a small amount of the recently-abused substance is needed to re-activate your buzz. So named after what happens in the shower when you "rinse and repeat": only a tiny bit of shampoo is needed the second time around to achieve a full sudsy lather.


"Man, I've only had one bloody mary and I feel buzzed!"

"Shampoo effect, dude. You were blasted last night."