costco effect

Over purchasing because the price per unit is too attractive to pass up.

Aw, Mike why did you buy three 48-ounce bottles of ketchup? The Costco effect got you. The second two are going to expire before you get to them.

The Costco Effect

That moment when you go to the store only needing a few things, then end up leaving with a whole cart of stuff, typically not including the original item(s) you came for. This term is not exclusive to Costco and can be used for any store that manages to get you to fall into its consumerist trap.

"Dang, look at all this stuff we bought. I only needed a couple of things !"

"That's the Costco Effect for ya"