Click on the image on the right to see the entire sketch at super-high resolution.
Below are my comments on specific details.
Marc is the easiest of my friends to draw, and his hair is fun here. I messed up Brian's chin, but it still looks like him even with sunglasses.
Marc's hand looks good here, and I think the folds of Brian's shirt work. Everyone's pelvises are at slightly different heights. Pelvises is not a word one has to spell often.
Ji has no hands.