I suppose she dumped the milkshake on him because the only thing he found to talk about was something that she already heard about and the same convo he already had with Riley. I didn't get why the show kept insisiting that for Lucas to date the person as to act like a Riley and for them not to to act like Maya. The last thing i would want is that cause they are pretty much having no one being their real self and it's one of the reason Maya and Lucas felt extra forced, because they weren't acting like themselves at all. They were acting like Lucas and Riley and it's just not at all the same type of connection.