My mouth just dropped when I saw that scene in Imaginationland. I died from happiness during that trilogy, it was ah-mah-sing. The makers really did not need to make him rub that photo to get the point across, but they chose to animate it either way. That should tell us something at least.
Also the fact that Cartman goes to court, crosses the country, obsessively searches for Kyle and breaks in a highly-secured goverment place JUST to get Kyle to suck his balls... That should make it obvious by itself.