By Diane Rommel Watching people walk past Luke Allen’s ceramics is an exercise in excessive good tidings. “Whoa,” someone will say. “Dude, I’m so stoked on all of this.” “This is amazing,” someone else will say. What do they see? They see a handbuilt ceramic “Average Watering Can” that can, in fact, function as a watering can (or a pipe) and also features a flesh-colored replica of an average-sized penis. (“I just want to really celebrate being average,” Allen says. “Being average is awesome!”) They see a cast of his tongue. They see one piece adorned with shavings from Allen’s curly ginger be…