This phrase is used by actor Eddie Griffin in "Deuce Bigalow: European Gigolo".
Russian women are a little freaky down there, hair start in the front, don't end 'till the back. So if you have to give a little mouth to south, put a clothespin on your nose.
A temporary but uncomfortable oral condition that occurs when consuming crunchy, sharped-edged food, resulting in painful trauma to the roof of the mouth. Examples of common food items that cause Mouth Beef are: Antiseptically dry sourdough toast, tortilla chips (if eaten in great gluttonous handfuls), and Cap'n Crunch® breakfast cereal (any variety).
Sorry, sweetcheeks, I can't make out with you tonight; I had five bowls of Cap'n Crunch this morning and have a terrible case of mouth beef.
1. Someone who is incapable of breathing through their nose
2. Someone stupid who is unaware that their mouth is gaping open, often taking in gallons of air and spewing their own dry, bacteria rotten maw into your clean air in your vicinity.
Never let a mouth-breather speak to you very close, or you might regret it.