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When a customer or client doesn't have their act together, thereby creating a headache and more work for you.
You just made a big sale, why are you all bitter?

The time I spent getting him to finally figure out what he wanted was ridiculous. That clustermer was way more trouble than he was worth.
by 11DMH69 July 20, 2010
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A small crowd of people who enter a store as a group.
Having clustermers come in can be a store-owner's dream-come-true if each of the members of the group buys a few items, but it can also be a nightmare if they all just want to use the restrooms.
by QuacksO June 23, 2018
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