Martin's immediately recognizable drawing style (which featured bulbous noses and the iconic hinged foot) was loose, rounded, and filled with broad slapstick. His inspirations, plots, and themes were often bizarre and at times bordered on the berserk. In his earliest years with "Mad", Martin used a more jagged, scratchy line. His style evolved, settling into its familiar form by 1964. It was typified by a sameness in the appearance of the characters (the punchline to a strip often was emphasized by a deadpan take with eyes half open and the mouth absent or in a tight, small circle of steadfast perplexity) and by an endless capacity for newly coined, onomatopoetic sound effects, such as "BREEDEET BREEDEET" for a croaking frog, "PLORTCH" for a knight being stabbed by a sword, or "FAGROON klubble klubble" for a collapsing building. (Martin's dedication to onomatopoeia was such that he owned a vanity license plate which read "SHTOINK," patterned after the style of his famed sound effects.)