Panel 2: The girl who's saying, "S'up, peeps?", did she just walk up? Because if she was already there, that's an odd thing to say in the middle of a conversation.
Panel 3: At first I thought April had her hand on that girl's shoulder, but it appears to be the guy's hand. What odd 1965 hair she has, too.
Panel 4: Pumpkinhead.
Well, I do have to give Lynn props, if that expression's not outdated already: most of these terms are in wide use. Even if they're a bit jumbled (Lynn, it's not "L.O.L."; it's just "LOL".) However, I find it hard to believe that April the Supercool is overwhelmed by her classmates' display of utter hipness.