Had the pleasure of going with a mate into the Celtic end for their end of season match at Hibs a couple of years back, both sets of fans so close that you can hear every shout between the two. Was pretty good natured, but I never stopped laughing for the entire 90 minutes.
Best one came at the end though, Celtic players came over to applaud, fans giving it good until Gary Caldwell comes over, clapping the fans and saying thanks. One guy jumps up and screams right at him "We're no clapping you Caldwell ya fuckin donkey!".