Misamplification can be seen when people say things like "he didn't just jump the shark, he jumped the beach, the lifeguard stand, and most of the cars in the parking lot." The reason this is a misamplification is that the metaphor is not about the height of the jump, it was an example of a purportedly low-quality episode of a popular TV program. You could say, "He didn't just jump the shark, he did it during sweeps week."
Misamplification can be applied to other metaphors as well: "He's not just circling the drain, he's circling the whole bathroom!" Instead, try "he's not just circling the drain, he's already half down it!"
Another misamplification example: "He's not a paper tiger, he's a rock, scissors and paper tiger!" A better option might be "He's not a paper tiger, he's more of a paper tiger's cub" or "he's not a paper tiger, he's a paper tabby cat."
Some misamplifications actually defeat the point: "He didn't just spit into the wind, he spat away from the wind as well!" Another: "It wasn't just coming up spades, but hearts, clubs, and diamonds too!"
I suppose there's also a special category of misamplifications. If someone tries to amplify "I am the door," into something more, it's likely going to end up just wrong. Same for "I am the vine." The Roman Catholics get a special award in this category when they amplify "this is my body" into "this is my body, blood, soul, and divinity," although perhaps they should be disqualified from receiving the award, since they mean it non-metaphorically. Thankfully for their teeth they don't make an identical error with "this cup" but instead refer those words to the contents of the cup.
Anyway, just something on my mind.
Oops, the original post included a simile, instead of a metaphor at one point:
So, for example, "that went over like a lead balloon" could be amplified as "that went over like a lead balloon filled with sand."My apologies to the reader