I do like how, deep down, Bobby carries the same kind of "do the right thing" attitude as his father, as we saw when he defended the girls even after they "dumped" him.
Though I must admit I'm a little confused about what the girls' motivations for befriending Bobby were. What was their "experiment"? To hang out with Bobby and then reveal that they weren't his girlfriends? I don't get it. Seems like the typical "I'm your friend, but not your girlfriend" shtick, only with three of them at once. They made it sound like he was their guinea pig for a psychological study they were conducting, which I think is giving them too much credit.