The definitions of the word lamer is usually pretty cheesy and stupid; they are almost always in association with structures like "is such a", "is totally a", or "acts like a".
These people probably spend their days at the malls and never even seen anyplace urban before, or are just uncreative.
Synonymous to n00b
Bob: Uhm... wow. What in the world did you just say dude?
Word Lamer Guy: Shut up man! Gosh, Bob always acts like a Gremkledopey!