1. A make believe sports car designed to appeal to those who are too poor and broke ass to afford a European car, who are jerk-off's, and hope to make friends with other waterheads who think their Honda Civic Si's are cool.(Also Si owners are sometimes liberal cowards, but they mostly drive Subaru Foresters)
2. An insult, usually aimed at anyone who falls in the above category, but there can be special exceptions.
1. My Honda Civic Si is so cool lolz, I think I'm going to go park near a handicap spot and pick up some babes!
2. Wow! That fat kid with the man tits in my gym class runs as fast a Honda Civic Si.