What? Oh wait, is this because northgate stopped selling full-sized pitchers? I forgot about that. What do most people do now? Get their own and do it at home? That's really sad if you can't do it at the bars anymore.
We buy the logo'd glass pitchers (bought mine at that store in the mall) and get everybody at the ring dunk to sign them. At least, that's what me and all my buddies did.
I know that I purchased one of the plastic ones from the Chicken when I dunked my ring two years ago. Not sure if they are "full" or not but it worked for me. Eventhough I had to do it off of NG.
I remember when we had to enforce the no dunk rule in the chicken, watched a guy down a pitcher of zeigen in 7 flat, couldn't even reach him before he finished it, i was so impressed i didn't even ask him to leave.