2.3 Direct Object

In English grammar, a direct object is a noun, noun phrase, or pronoun that identifies what or who receives the action of a transitive verb in a sentence.

I (s) just wanna eat (v) dinner (direct obect).

When we use a pronoun as a direct object, it takes the form of the objective case, which means we use the pronouns me, you, him, her, it, us, them, whom, whomever, and what.

Megan (s) bought (v) it (d/o, objective case) for you (indirect object). 

Source: http://grammar.about.com/od/d/g/dirobjecterm.htm