Like when you wash your hair a second time in a row you get much more lather. The lather effect refers to when you get intoxicated a second night in a row, you get much more intoxicated.
"So remember, my friends, if you’re going to rinse and repeat always beware the extra bubbles." -- From the movie "The Lather Effect"
"I partied 3 days in a row, the lather effect was going strong."