Used by probationers who aren't allowed to drink alcohol to explain why they fail breathalyzers. Similar to the toothpaste defense, the cough syrup defense, and the hand-sanitizer defense, the latter of which only applies to ETG tests (Urine alcohol tests).
Probation officer: You failed your breathalyzer.
Probationer: I didn't drink alcohol, I just used mouthwash before I came here.
Probation Officer: That's the mouthwash defense. It's bullshit and you know it. You're going to jail.
Probationer: I didn't drink alcohol, I just used mouthwash before I came here.
Probation Officer: That's the mouthwash defense. It's bullshit and you know it. You're going to jail.
by Lupara2012 August 1, 2012
Get the mouthwash defensemug.