I'm 31. I've been out of high school for quite some time. The "I'm older than you so I know better" is a nice rhetorical trick, though, because the only way the argument can go from there is:
"Uh-uh."
"Uh-huh."
"Uh-uh."
"Uh-huh..."
Oh, but wait, I can already guess your next post:
"Well gee, Chris, given the immaturity and naivette of your post, I just ASSUMED you were still in your mid-teens..."
;)