Possible Clues:

• Richie's dad, to the Fonz
• Howard Cunningham, to Fonzie
• "Happy Days" nickname
• Richie's dad, to Fonzie
• What the Fonz called Richie's dad
• What the Fonz called his landlord
• Howard Cunningham, informally
• ''Happy Days'' dad, to Fonzie
• Shortcake's dad, to Fonzie
• Address used by Fonzie