Humor happens when something violates your expectations in a benign way. You expect A, you get B. The surprise creates a momentary cognitive jolt, which gets resolved as humor. Nerhardt (1970) documented this: incongruity (expectation violation) is the core mechanism of humor.1
The paradox: humor ads are historically associated with lower purchase intent. Shotton notes a 53% to 34% decline in usage when humor was featured in advertising. Yet humor creates memorability and likeability. This creates a tension: humor makes ads memorable but less persuasive.
The resolution: humor works best when it's integrated with the product benefit, not separate from it. Snickers' "You're not you when you're hungry" uses humor incongruously—grumpy people becoming absurd versions of themselves—but the humor proves the benefit (hunger changes behavior).
Your brain predicts what should happen. When reality violates that prediction, you experience surprise. If the violation is threatening, you get fear. If it's benign (safe to laugh), you get humor.
The key: the violation must be surprising enough to violate expectations, but safe enough to not trigger threat response. Snickers does this perfectly: you expect grumpiness to be temporary, but the ads show it transforming behavior absurdly. The incongruity is surprising but safe (the resolution shows how to fix it).
Step 1: Identify the expected behavior in your context What do customers expect to happen? In fast food, they expect indulgence without concern. In financial services, they expect seriousness.
Step 2: Create incongruity that proves your benefit Don't use humor for humor's sake. Use it to violate expectations in a way that demonstrates the benefit. Snickers shows unexpected behavior (absurd grumpiness), then resolves it with the product.
Step 3: Keep the incongruity close to the benefit The humor shouldn't be separate from the claim. It should prove the claim through surprise.
Step 4: Test persuasion alongside memorability Humor increases recall but can decrease persuasion. Test both metrics. If recall rises but persuasion drops, the humor isn't integrated enough with the benefit.
Humor in high-credibility categories (banking, law, medicine) can backfire. The incongruity suggests "this category isn't serious," which violates the expectation that seriousness = competence. For luxury or professional services, humor dilutes rather than enhances.
Behavioral-Mechanics → Expectation Assimilation: Incongruity works by violating expectations. The expectation gets assimilated to the violation. Expectation Assimilation explains how the incongruity gets encoded into memory.
Psychology → Von Restorff Effect: Humorous ads stand out as distinctive because the incongruity is memorable. Von Restorff Effect explains why humor creates stronger memory traces.
Sharpest Implication: Humor is powerful for memorability but risky for persuasion. The move is to integrate humor with the actual benefit so the humor proves the benefit rather than distracting from it. Humor that just entertains backfires. Humor that demonstrates is powerful.