Ord's ladybug helmet in "A Liking to Biking." First, there's the fact that he creates the helmet by grabbing an actual ladybug, then pulling down its legs and tying it onto his head. Then, throughout the remainder of the episode when he has it on, its expressions mimic his.
The Grudge in "The Grudge Won't Budge" is a riot. First, there's his smarmy, wheedling voice with accompanying Leitmotif that plays every time that speaks. Second, he's The Nicknamer, calling Zak various "Zackarooni, "Zakster" and about a dozen other names. Then there's the irritated reaction he inspires in the other characters. There's also his reaction when Zak & Wheezie finally start to talk things out and Zak admits to feeling hurt because Wheezie broke his snoot flute— "Whoa! Just stick with being angry. It's easier." Finally, the way he reacts when Zak finally gives him the big shove— "I thought I'd finally found somewhere to stick around for a while."