Or as translated in the movie:
Randy yacía como un plomo.  Esa fue defensa.

Once again you probably won't be able to ever use that phrase.   But we can at least not only learn some  vocabulary words, but also how to make a comparison.    Yacía is a form of the verb "yacer" which means "to lie or to be lying."  Plomo means "slug", but not the animal.  It actually means slug when you are referring  to a coin-like object made of lead.  These were used to try to cheat vending machines.  The word that means the animal slug (which was meant in this sentence) is "babosa".  It was seem that this would be a mis-translation because in English we  use the word slug, meaning animal, in this phrase.  In Spain they use the word slug, meaning lead object, when they use this term.  So it is actually translated correctly.    

Como is used for making comparisons (habla como su padre - he talks like his father).

Esa means "that".  Fue is a form of the verb "ser" which means "to be".   It this sentence it means "was".  Defensa means "defense".  What is actually said is "That was his defense".  The word "only" is omitted in the translation.  Note that at the beginning of the sentence esa was used instead of ese.  They both mean "that", but esa is used because it refers to defensa which is a feminine noun.

Here are some more simple phrases.   When there is a name just substitute any name.

¡Más alto!
Louder!
Más means "more".  It can also be used for comparisons (es más inteligente que yo - she is more intelligent than me).   Alto not only means "loud", but also "high".  To tell someone to speak up you would say "¡habla más alto!" 

No importa.
No matter.
Importa means "important".  By saying "no importa" you mean it is "not important".  

¡Un premio gordo!
A major prize!

Premio means "prize or award".  Gordo means "important".  Gordo can also mean "fat". To a person from Spain "el gordo" refers to a lottery that is held each year in December.  

No sé.
I don't know
Sé is a form of the verb "saber" which means "to know".